Mehdi Hassan was born on 18 July 1927 in a village called Luna, Rajasthan, in India. He hailed from a family with a rich musical legacy—he claimed to be the 16th generation of hereditary musicians hailing from the Kalawant clan of musicians. His ancestors were "Darbari Ustads", seasoned performers in the courts of several Maharajahs of Indore, Patna, Chhatarpur and Mysore.

He was trained for a career in music from a young age. As a little boy, he started receiving lessons from his father Ustad Azeem Khan and uncle Ustad Ismail Khan who were both traditional Dhrupad singers. He did not receive any formal education other than his music training.

He started performing at a young age and reportedly gave his first concert with his elder brother in Fazilka Bungla.

The partition of India in 1947 greatly affected the fortunes of the Muslim family. When the new nation of Pakistan was created, Hassan, along with his family migrated to Pakistan. Hassan was 20 years old at that time.

The family had been well established in India but lost everything during the partition. Having moved to a new nation, they struggled to re-establish themselves. Mehdi took up a job in a bicycle shop Mughal Cycle House to make ends meet.

Eventually he became a car and diesel tractor mechanic. His daily life was a struggle, yet he never gave up on practicing his art and was still determined to make it big as a singer.

He received the opportunity to sing classical vocal for Radio Karachi in 1952. This gave him an opportunity to reach to a wide audience and he soon became popular as a ghazal singer with his deep, sonorous voice. He proved his mettle as a classical singer by rendering challenging raga-based compositions and endeared himself to the listeners.

During this period he created some memorable ghazals like ‘Ranjish hi sahi’, ‘Baat karni mujhe mushkil’, ‘Ghazab kiya tere wade pe’ and ‘Gulon mein rang bhare’. By the mid 1950s his stature as a ghazal singer was rising.

In 1957, Mehdi Hassan was given the opportunity to sing on Radio Pakistan. He initially started off as a thumri singer and earned much acclaim for his talent. He also wrote Urdu poetry and composed ghazals, and with encouragement from radio officers Z.A. Bukhari and Rafiq Anwar, he started singing ghazals as well.

He earned much acclaim as a ghazal singer and soon ventured into films as well. In 1962, he sang ‘Jis ne mere dil ko dard diya’ for the film ‘Susral’. He got a big break in 1964 when he sang ‘Gulon mein rang bharay, baad-e-naubahar chale’ for the film ‘Farangi’. This ghazal proved to be a major hit and cemented his career as a much sought after ghazal singer in Pakistani cinema.

Over his illustrious career, he provided sound tracks for nearly 300 movies and produced several soulful and touching ghazals that won him thousands of fans not just in Pakistan, but also in India. He also received considerable recognition for his contributions to classical music.

Mehdi Hassan was famously known as the "King of Ghazal" or the "Shahanshah-e-Ghazal” and is considered next only to Begum Akhtar in the world of Ghazal Gayeki. Some of his most famous ghazals are ‘Ranjish hi Sahi’, ‘Baat karni mujhe mushkil’, ‘Ghazab kiya tere waade pe’ and ’Gulon mein rang bhare’.

He was duly honored by the Government of Pakistan with several awards including Pride of Performance, Tamgha-e-Imtiaz, Hilal-e-Imtiaz, and Nishan-e-Imtiaz.

The Government of Nepal decorated him with Gorkha Dakshina Bahu in 1983 and the Government of India bestowed upon him the K. L. Saigal Sangeet Shahenshah Award.

He was also the recipient of several Nigar Awards, the official awards of Pakistani film industry to honor the show business personalities of Pakistan.

Mehdi Hassan was married twice. He had 14 children, many of whom became acclaimed singers in their own rights.

He started suffering from ill health in the late 1980s, especially from a serious lung condition. He died on 13 June 2012, aged 84.