Singh was born on 25 April 1987^[1] in Jiaganj, Murshidabad, West Bengal to a Punjabi father and a Bengali mother.^[5] He initiated training in music from his house, since his maternal grandmother used to sing and his maternal aunt is trained in Indian classical music. His maternal uncle also plays the tabla. He also learnt music from his mother who sings and plays the tabla. For studies, he went to Raja Bijay Singh High School and Sripat Singh College, a University of Kalyani affiliate.^[6] According to Singh he "was a decent student, but cared more about music". His inclination towards music led his parents to decide on training him professionally. He was taught Indian classical music by Rajendra Prasad Hazari and trained in tabla by Dhirendra Prasad Hazari while Birendra Prasad Hazari taught him Rabindra Sangeet and pop music.^[6][7]

In 2005, Singh auditioned for the reality show Fame Gurukul, insisted by Rajendra Prasad Hazari since he felt that "classical music was a dying tradition".Initially being hesitated of taking that chance, Singh joined the show since composer Shankar Mahadevan was included in the jury panel and he has a classical background and "astounding versatility".Though Singh lost the show to the finals, he entered another reality show, 10 Ke 10 Le Gaye Dil, which is a musical face-off between the winners of Fame Gurukuland Indian Idol.After winning the show, Singh built a recording setup of his own, beginning his journey with music programming. Subsequently, he went to become as an assistant music programmer to Shankar–Ehsaan–Loy, Vishal–Shekhar and Mithoon. During the time, Mahadevan once tried to convince a producer to retain Singh’s version of a certain song that he was composing, saying Arijit is the voice of the future. But the producer refused, claiming that he wants a "popular" voice. Eventually Mahadevan dubbed the song with another singer.

In 2010, Singh started working with Pritam Chakraborty on three films—Golmaal 3, Crook and Action Replayy.During the time, he started singing scratches on Chakraborty's insistence. In 2011, Singh made his Bollywood music debut with theMithoon-composition, "Phir Mohabbat" from Murder 2, which was recorded in 2009 though released in 2011.The same year, when he was programming the song "Raabta" from Agent Vinod (2012), Chakraborty wanted him to sing the classical arrangement in the song. The part was retained in the four versions of the song, and made him to sing the entire composition in one of the versions.Apart from Agent Vinod, Singh dubbed for Chakraborty in three other films released during the year; Players, Cocktail and Barfi!. He also lent his voice for Chirantan Bhatt in 1920: Evil Returns and forVishal–Shekhar in Shanghai, where the song "Duaa" from the latter fetched him Mirchi Music Award for Upcoming Male Playback Singer award and was nominated in the same category for "Phir Le Aya Dil" from Barfi!.

Singh rose to widespread prominence with the release of the song "Tum Hi Ho" from Aashiqui 2 (2013). The song fetched him several awards and nominations including Filmfare Award for Best Male Playback Singer. He worked with Jeet Gannguli for the rest of his tracks in the album. Gannguli was searching for a "fresh voice" for the film, when he stumbled upon Singh's "Duaa" on YouTube. Singh further allied with Chakraborty, singing "Dilliwaali Girlfriend", "Kabira" and "Ilahi" for Yeh Jawaani Hai Deewani.Other than rendering the encore version of "Kabira", he was associated as the music producer of the track along with "Balam Pichkari" from the same film. Singh considered the period as a "lean phase" which helped him in becoming a "better" musician.The duo collaborated with Shahid Kapoor, performing "Main Rang Sharbaton Ka" from Phata Poster Nikhla Heroand "Dhokha Dhadi" from R... Rajkumar. Moreover, he dubbed for Shah Rukh Khan in the song "Kashmir Main Tu Kanyakumari" from Chennai Express which was composed by Vishal–Shekhar.Apart from rendering the duet version of "Har Kisi Ko" from Boss along with Neeti Mohan,the year marks his collaboration with Sharib–Toshiand Sanjay Leela Bhansali by singing the song "Kabhi Jo Baadal Barse" from Jackpot for the former and the semi-classical number, "Laal Ishq" from Goliyon Ki Raasleela: Ram-Leela for the latter.While Singh picked "Kabhi Jo Baadal Barse" as one of his personal favorite songs, he chose "Tose Naina" from Mickey Virus as "closest to his heart".

In 2014, Singh got the chance to work with two of his favorite music directors, Sajid–Wajid and A. R. Rahman. He performed two tracks of Main Tera Hero and the song "Raat Bhar" from Heropanti for the former, and dubbed the Hindi version of the song "Medhuvaagathaan" from Kochadaiiyaan titled "Dil Chaspiya" for the latter.He rendered three re-mixed songs; Amit Trivedi's "Hungama Ho Gaya",Sharib–Toshi's "Samjhawan"and Arko Pravo Mukherjee's "Aaj Phir". Singh worked with Vishal Bhardwaj, recording two songs from Haider and with Sachin–Jigar for "Jaise Mera Tu" in Happy Ending.The year marks his collaboration with many other music directors includingTony Kakkar and Palash Muchhal.During the year, he provided vocals for Mithoon in "Humdard"and "Hai Dil Ye Mera", Vishal–Shekhar in "Manwa Laage",Shankar–Ehsaan–Loy in "Sajde", Sharib–Toshi in two songs of Zid and Pritam Chakraborty in three tracks of Holiday which was arranged by Singh himself.Gannguli-composedMuskurane garnered him most nominations in the year, while he received two Filmfare nominations for Suno Na Sangemarmar and the Sufi song Mast Magan.Singh picked "Gulon Mein Rang Bhare"—originally sung by Mehdi Hassan and re-composed for Haider by Vishal Bhardwaj—as his most favorite track from the year.

In 2015, Singh made his Tamil debut with the song "Neeye Vaazhkai Enben" from the film Pugazh.He also provided vocals for the song "Sooraj Dooba Hain" from Roy, which was composed by Amaal Mallik, who wanted "a voice that does not sing many peppy numbers" for the track. During the year, he again worked with Mallik in the song "Khwaishein" from Calendar Girls. Apart from dubbing the Hindi version of the song "Pookkalae Sattru Oyivedungal" from Rahman's I, along with Shreya Ghoshal, Singh teamed up with Gannguli and Bobby–Imran for Khamoshiyan, where he performed the title song of the film and "Baatein Ye Kabhi Na" for the former and "Tu Har Lamha" for the latter.He collaborated with Gannguli in two other projects; "Teri Khushboo" from Mr. X and the title track of Hamari Adhuri Kahani.Besides working with Bhatt for "Teri Meri Kahaani" and Sachin–Jigar for "Chunar", he worked with some new composers like, Bann Chakraborty,Khamosh Shah,Jatinder Shah,and Manj Musik. Moreover, Singh recorded a reprise version of Sonu Nigam's 1999 song "Deewana Tera" for Ek Paheli Leela. The year marks the first collaboration of Singh and Himesh Reshammiya, with the song "Baaton Ko Teri" from All Is Well.Furthermore, he voiced for Bhardwaj in "Shaam Ke Saaye" and "Kya Pataa"from Talvar and Drishyam respectively, while he performed Phantom's "Saware" and "Sooiyan" from Guddu Rangeela, which he considered one of the few compositions close to his heart. Apart from recording for soundtracks of the film, Singh released his second promotional single during the year. Titled, "Chal Waha Jaate Hain", the song is composed by Mallik, featuring Tiger Shroffand Kriti Sanon. Recently, Arijit made his marathi debut with the song "Yaar Illahi – Qawwali" from the film Katyar Kaljat Ghusali.

In 2015, Chinmayi Sripada has recorded a romantic duet titled 'Sooiyan', written by talented Irshad Kamil and Amit Trivedi, with Singh for the Bollywood film Guddu Rangeela.