Turkish Airlines, originally known as Türkiye Devlet Hava Yolları (TDHY), started its operations with just 5 aircraft including two Curtiss Kingbirds, two Junkers F 13s, and one Tupolev ANT-9. The airline was led by Mehmet Fesa Evrensev, the first Turkish Ottoman aviator.

In 1935, the airline was turned over to the Ministry of Public Works and was subsequently renamed General Directorate of State Airlines.

In 1945, the first Douglas DC-3 was added to the fleet, while the first international flight, Ankara-Istanbul-Athens, took place two years later.

Turkish Airlines commenced international services with the inauguration of Ankara–Istanbul–Athens flights in 1947, expanding its network with the introduction of Douglas DC-3s and Douglas C-47s.

Yeşilköy Airport, later renamed Atatürk Airport, was inaugurated in 1953, providing Turkish Airlines with a modern hub for its operations. This new airport facilitated the airline's growth and connectivity.

On the 21st of May 1955, the title “General Directorate of the State Airlines Administration” has been changed by Law number 6623 to its current name: Turkish Airlines.

In 1956, Turkish Airlines was reorganized by the government, leading to its renaming as Türk Hava Yolları (Turkish Airlines). This reorganization also resulted in the airline gaining international recognition through its IATA membership.

In 1957, Turkish Airlines entered into a technical partnership with the British Overseas Airways Corporation (BOAC) after BOAC acquired 6.5% of the airline's shares. This partnership lasted for approximately two decades.

In 1958, Turkish Airlines modernized its fleet by adding 5 British-built Vickers Viscount 794 turboprop aircraft, replacing the aging DC-3s and C47s. This marked a significant step towards modernization for the airline.

A Vickers Viscount Type 793 carrying Turkish Prime Minister Adnan Menderes and a governmental delegation to London crashed in dense fog on approach to London Gatwick Airport. Nine passengers and five crew members lost their lives.

Turkish Airlines Flight 835, a Fokker F27-100, crashed at Karanlıktepe in Ankara Province on approach to Esenboğa Airport. All crew members and 24 out of 25 passengers were killed.

A Fairchild F-27 crashed into the Taurus Mountains on approach to Adana Şakirpaşa Airport. All crew members and passengers on board died.

A Douglas C-47 on a domestic cargo flight flew into terrain while on approach to Esenboğa Airport, Ankara. All three crew members on board were killed.

In 1966, Turkish Airlines introduced the McDonnell Douglas DC-9 jet to its fleet, marking the airline's entry into the jet age. The DC-9 was a key addition to the growing fleet of Turkish Airlines.

On 1967, the first international jet flight has been realized on the Ankara-Istanbul-Brussels line.

A Vickers Viscount Type 794 crashed on approach to Esenboğa Airport. There were no casualties.

In 1971, Turkish Airlines added the four-engined Boeing 707 to its fleet, further expanding its jetliner offerings. The airline went on to operate 17 aircraft from the Boeing 707 family.

The widebody DC-10 jetliner was introduced to Turkish Airlines' fleet in 1972, enhancing the carrier's long-haul capabilities and aircraft diversity.

Turkish Airlines Flight 301, a Fokker F28-1000, crashed shortly after takeoff from Izmir Cumaovası Airport due to atmospheric icing on the wings. 4 crew members and 62 passengers were killed.

On March 3, 1974, Turkish Airlines Flight 981, a McDonnell Douglas DC-10, crashed into Ermenonville Forest, France, due to explosive decompression, resulting in the death of all 335 passengers and 11 crew members. The crash was caused by a design fault on the cargo doors of the aircraft.

Turkish Airlines Flight 345, a Fokker F28-1000, crashed into the Sea of Marmara during final approach to Istanbul Yeşilköy Airport on January 30, 1975, leading to the deaths of all 4 crew members and 38 passengers on board.

On September 19, 1976, a Boeing 727-200 operating as Turkish Airlines Flight 452 crashed into the Karatepe Mountains due to pilot error during an attempted landing in Isparta instead of Antalya. The accident resulted in the loss of all eight crew members and 146 passengers on board.

A Fokker F28-1000, flying from Samsun-Çarşamba to Esenboğa Airport, crashed in Kuyumcuköy village in severe turbulence on December 23, 1979. The accident resulted in the deaths of three crew members and 38 passengers.

Turkish Airlines Flight 158, a Boeing 727-200, landed short of the runway at Esenboğa Airport in driving snow on January 16, 1983. The aircraft broke up and caught fire, leading to the death of 47 out of 60 passengers on board.

In 1984, the company's capital was raised to TRL 60 billion as it was classified as a state economic enterprise. A new technical facility is constructed as the airline begins a turnaround.

Turkish Airlines started operating Airbus A310s in 1985, enabling the addition of flights to Singapore.

In 1986, Turkish Airlines expanded its flights to Singapore.

In 1987, Turkish Airlines (THY) experienced financial losses as a result of the significant payments associated with acquiring twelve new Airbus A310s.

In 1988, Turkish Airlines (THY) continued to face financial challenges due to the substantial payments required for the twelve new Airbus A310s in its fleet.

On 1989, The Baggage Handling System (BAHAMAS) has begun to be implemented in order to provide rapid baggage services.

In 1990, Turkish Airlines (THY) placed an order for five Airbus A340 aircraft with the option for five more, aiming to operate non-stop flights to North American and East Asian destinations.

In 1991, Boeing 737s were added to the fleet, and the registered capital reached 2 trillion TL.

In 1993, Turkish Airlines (THY) received its first Airbus A340 aircraft, three years after placing the initial order in 1990.

On 1994, 27th of November, the airline attained the status of being a state owned enterprise.

Turkish Airlines Flight 278, a Boeing 737-400, crashed during its final approach to Van Ferit Melen Airport in driving snow on December 29, 1994. The crash resulted in the deaths of five crew members and 52 passengers.

In 1995, Turkish Airlines (THY) increased its capital to 10 trillion TL and converted three Boeing 727s into dedicated freighters. The company also saw profitability, posting a $6 million profit on revenues of $1 billion.

The domestic aviation market in Turkey was deregulated in 1996, allowing new scheduled competition from charter airlines. Turkish Airlines (THY) had to adapt to increased competition and market changes.

In 1997, Turkish Airlines (THY) entered into marketing agreements with international carriers like Japan Airlines, Austrian Airlines, Swissair, and Croatia Airlines. The airline also began operating flights to Chicago as part of its expanding international network.

Turkish Airlines (THY) partnered with Japan Airlines in 1998 to offer service to Osaka and Tokyo, enhancing their global reach and network. This collaboration was part of THY's strategy to strengthen its presence in the East Asian market.

On 7 April 1999, Turkish Airlines Flight 5904, a Boeing 737-400, crashed near Ceyhan, Adana shortly after taking off from Adana Şakirpaşa Airport. The crash resulted in the loss of all six crew members on board.

On October 29, 2000, Turkish Airlines (THY) decided to withdraw from the Qualiflyer alliance led by Swissair, aiming to attract a strategic investor for their privatization. This move marked a strategic shift in THY's alliances and partnerships.

In 2001, Turkish Airlines (THY) expanded its route network by adding an Antalya-Frankfurt route through a code-sharing agreement with Sun Express. This partnership enabled THY to enhance its connectivity and offer more travel options to passengers.

Turkish Airlines Flight 634, an Avro RJ-100, crashed on approach to Diyarbakır Airport on 8 January 2003. The crash led to the tragic deaths of all five crew members and 70 passengers aboard the aircraft.

The Turkish Airlines Flight Academy (TAFA) was established on November 10, 2004, by the 28th THY Board. It began training activities with 16 cadets on May 1, 2006.

In 2005, Turkish Airlines divested its 50% holding in Cyprus Turkish Airlines as part of its strategic decisions in the aviation market. The move was made amidst a booming tourism industry in Turkey.

Turkish Airlinws decided to join the Star Alliance on the 4th of August, 2006.

On 3 October 2006, Turkish Airlines Flight 1476 en route from Tirana, Albania to Istanbul was hijacked by Turkish citizen Hakan Ekinci in Greek airspace. The hijacker surrendered after a forced landing in Brindisi, Italy.

In 2007, Turkish Airlines' Star Ranking status was upgraded to that of a 4 Star Quality Certified Airline.

On April 1, 2008, Turkish Airlines became the seventh European airline to join the Star Alliance after an 18-month integration process. This move expanded the airline's global network and connectivity.

Turkish Airlines Flight 1951, a Boeing 737-800, crashed during final approach to Amsterdam Airport Schiphol on 25 February 2009. The crash was attributed to a faulty radar altimeter and crew error, resulting in the loss of nine lives.

On 2010, Skytrax, a traveller website based in the UK, rated Turkish Airlines Europe’s best for 2010.

In December 2011, the Turkish government announced plans to upgrade the Aden Adde International Airport in Mogadishu, Somalia, as part of Turkey's involvement in the post-conflict reconstruction process. The project included the installation of new airport systems and infrastructure, such as a modern control tower.

In March 2012, Turkish Airlines became the first international carrier to resume flights to Somalia since the country's civil war in the early 1990s. This marked a significant milestone in the airline's operations and its commitment to connecting regions affected by conflict.

On 22 October 2013, Turkish Airlines and Euroleague signed an agreement to prolong their existing sponsorship deal by five years until 2020. Turkish Airlines has been the primary sponsor of the Turkish Airlines EuroLeague since 2010.

In 2014, Turkish Airlines presented the first aircraft equipped with new seats created through a partnership.

Turkish Airlines Flight 1878, an Airbus A320-200, was severely damaged in a landing accident at Istanbul Atatürk Airport on 25 April 2015. Fortunately, all occupants were safely evacuated without any reported injuries.

On 10 December 2015, Turkish Airlines and UEFA signed a sponsorship deal for the UEFA Euro 2016, becoming the first airline sponsor of UEFA European Championship tournaments.

On January 29, 2016, Turkish Airlines announced a partnership with Warner Bros. to sponsor the film Batman v Superman: Dawn of Justice. The movie featured a scene on a Turkish Airlines A330.

Following the 2016 Turkish coup d'état attempt, the Federal Aviation Administration imposed a temporary ban on flights between Turkey and the United States. This ban disrupted Turkish Airlines' operations, impacting its strategy of providing one-stop journeys to various regions.

On 16 January 2017, Turkish Airlines Flight 6491, a Boeing 747-412F operated for Turkish Airlines under wet lease from ACT Airlines, crashed into a residential area upon attempting landing in Manas International Airport in Bishkek, Kyrgyzstan, resulting in the deaths of all four crew members and 35 people on the ground. Turkish Airlines initially distanced themselves from the incident, but it was still considered a Turkish Airlines flight under IATA rules.

On September 14, 2018, Turkish Airlines signed a sponsorship agreement with Lega Basket Serie A, the top-tier professional basketball league in Italy, becoming an official partner for the 2018–19 LBA season.

On 21 November 2019, Turkish Airlines Flight 467, a Boeing 737-800, experienced a nose gear collapse while landing in heavy crosswinds at Odesa International Airport in Ukraine. Fortunately, all passengers and crew were safely evacuated using emergency slides without any injuries. The aircraft, with registration TC-JGZ, was deemed a hull loss and was later scrapped in 2020.

In February 2020, Turkish Airlines added its 319th destination to its flight network, the capital of Equatorial Guinea.

Despite facing challenges during the pandemic, Turkish Airlines swiftly resumed its services in January 2021, serving 208 destinations compared to 317 before the pandemic.

By February 2021, Turkish Airlines emerged as the largest carrier in Europe by passenger volume, surpassing other leading airlines like Air France-KLM, Lufthansa, British Airways, Ryanair, and easyJet.

As of August 2021, Turkish Airlines has a mixed fleet of 374 aircraft from Airbus and Boeing, with outstanding orders for the 787 and A350, as well as a large order for the A321neo.

On 26 January 2022, İlker Aycı resigned from his position as chairman of Turkish Airlines. The next day, Ahmet Bolat was elected as the new chairman.

On 11 May 2023, Turkish Airlines announced the purchase of around 600 new aircraft over a period of 10 years. The majority of the aircraft will be from Airbus and Boeing, with some from another manufacturer.

As of March 2024, Turkish Airlines operates a fleet of 365 aircraft. The airline has a rich history of fleet development, starting with five aircraft in 1933 and making significant additions over the years.