Hemanta Kumar Mukhopadhyay has been established as an accomplished singer of Bengali and Hindi songs after his introductory appearance on All India Radio in the late 1930s. This was made possible because of the influence of his friend Subhash Mukhopadhyay. He is also counted as one amongst the advocators of Rabindra sangeet, the songs of the most famous Bengali poet of the 20th century, Rabindranath Tagore. the Bengali musician Sailesh Duttagupta has been considered as the mentor in the musical life of Hemant Kumar. Till the year 1984, Hemanta started recording non-film discs for the Gramophone Company of India(GCI) and continued every year. In the year 1940 under GCI's Columbia label, Hemanta Kumar sung his first hindi songs 'kitanaa dukh bhulaaya tumane' and 'o priit nibhaabewaalii'.
'Katha koyonako shudhu shono' and 'amar biraha aakaashe priyaa' were the first compositions by Hemanta Kumar in the year 1944. Under Pt. Amarnath's music direction his first Hindi film songs were in Iraadaa released in the year 1944. The Bengali film 'Abhiyatri' in the year 1947 was his first movie as a music director. During the mid 1940's, Hemanta kumar as an active member of the Indian People's Theatrical Association (IPTA) came in association with songwriter and composer - Salil Chowdhury another active IPTA member. Theiy in a joint venture recorded a non-film song called 'gaaNyer badhu' (literally translates to 'The rural bride'). This song expressed 'an idyllic, prosperous and caring rural woman's life and family, and how it gets ravaged by the demons of famine and ensuing poverty'. This composition also moved the eastern India and the recognition of the pair of Hemanta Kumar and Salil Chowdhury has been established. Over the years this pair proved to be surprisingly sucessful.
Later on in then Year 1951, when Hemanta Kumar venturing her career in Mumbai (Then Bombay), he got the opportunity to direct music compositions for the film Anandmath(1952) under the banner of the Filmistan Studios. The career of hemanta Kumar geared up in Mumbai. He has also earned the honor of being a playback singer. Under music director Sachin Dev Burman, Hemanta Kumar has lent his voice in the movies like 'Jaal', 'House No. 44', and 'Solva Saal' for actor Dev Anand that were became quite popular. By the mid-fifties, Hemanta Kumar establisbhed himself as most aspiring singer and composer. Some hindi movies done by Hemanta Kumar as composer to note are, Anjaan, Anupama, Bahu, Bandhan, Bandi, Bandish, Bees Saal Baad, Bees Saal Pehle, Bhagwat Mahima, Bin Badal Barsaat, Biwi Aur Makaan, Chand, Champakali, Daku Ki Ladki, Do Dil, Do Dooni Char, Do Ladke Dono Kadke, Do Mastane, Durgesh Nandini, Ek hi Raasta, Ek Jhalak, Ferry, Faraar, Fashion, Girl Friend, Hamara Watan, Hill Station, Hum Bhi Insaan Hai, Jagriti, Khamoshi, Kohraa, Kitna Badal Gaya Insaan, Nagin, Nayakeenicha Sajja, Sahara, Sahib Bibi Aur Ghulam, Samrat, Sannata, Shart, Yahudi Ki Ladki.
Hemanta Kumar as a composer has composed music for bengali films like, Abhiyatri, Purbaraag, Bhuli Naai, Padma Pramatta Nadi, Priyatama, Diner Par Din, '42, Sandipan Pathshala, Swami, Jighansa, Shapmochan, Suryamukhi, Shesh Parichay, Taser Ghar, Harano Sur, Lookochuri, Shikar, Surjotoron, Joutuk, Neel Akasher Neechey, Deep Jweley Jai, Khelaghar, Marutirtha Hinglaj, Sonar Harin, Kshaniker Atithi, Baishey Shravan, Gariber Meye, Kuhak, Khoka Babur Prayabartan, Shesh Paryanta, Dui Bhai, Agni Sanskar, Madhya Rater Tara, Punashcha, Saptapadi, Sathi Hara, Swaralipi, Atal Jaler Ahwan, Agun, Dada Thakur, Hansuli Banker Upakatha, Nabadiganta, Badshah, Barnachora, Ek Tukro Agun, High Heel, Palatak, Saat Pake Bandha, Shesh Prahar, Tridhara, Adwitya, Baghini, Hansamithun, Jiban Sangeet, Panchasar, Parisodh, Din Amader, Hatey Roilo Tin, Mantramugdha, Pratima, Proxy, Rajani, Sanai, Shesh Raksha, Swati, Anindita, Shriman Prithviraj, Agni Shuddhi, Ajantay, Bishabriksha, Didi, Madhuban, Pratibha, Tunibou, Agaman, Boba sanai, Parasmoni, Surer Sathi etc.
Later on with movies of an unquestionably occidental cast, like Bees Saal Baad based on The Hound of the Baskervilles and Kohraa derived from Daphne du Maurier's Rebecca, Hemant Kumar diversified into film production. Even today, he has been recognized as one of the world-beating advocators of Rabindrasangeet and possibly the 'most sought after male singer'. Hemant Kumar remains a chairing role model even after his death in 1989 that other male Indian singers resemble.