O Kadhal Kanmani is the soundtrack album, composed by A. R. Rahman, to the 2015 Indian Tamil film of the same name written and directed by Mani Ratnam.

[2] Upon release, the soundtrack album garnered positive reviews from the music critics who praised the fusion of classical and contemporary genres, sync of songs with film narration and the production quality.

[14] In an interview with Deccan Chronicle, Rahman mentioned that his request to Mani Ratnam, a complete song was dropped after filming because of the explicit lyrical content.

[16] Rahman recalled that while writing Mental Manadhil, both he and Ratnam wanted an interesting invention of new words or phrases for the song.

During their jamming sessions—Rahman was saying 'Laka Laka' to rhyme with 'Mana Mana... Manadhil...' Ratnam said 'mental' and they decided to coin 'mental' and 'manadhil' together and thus hook words were framed.

It was a "soft song" that Ratnam wanted to be more energetic, on the lines of "Endrendrum Punnagai" (from Alaipayuthey) with more indipop sound to it.

[26] "Parandhu Sellu Vaa" was composed using the iPad app "Loopy", which creates loops, since Ratnam wanted it to feature minimal orchestration.

[24] When the phrase "Nanaindhu Kollava" appears at the middle of the song, the minimal violin based orchestration begins and runs until the end of the track.

The song starts off with a lot of auto-tune but diminshes when the female vocals begin, blending of classical music.

[29] Writing for The New Indian Express, Vipin Nair noted, "Mani Ratnam still does manage to turn A R Rahman into his inventive best!

[30] Critics of BollywoodLife called the music by A. R. Rahman a big hit and commendable job done for background score.

[31] M. Suganth for The Times of India wrote, "A. R. Rahman's hip songs and background score, keeps the scenes throbbing in the film.

"[33] Anupama Subramaniam of Deccan Chronicle opined that Ratnam and Rahman had created magical musical.

"[34] Kavitha Muralidharan for India Today summarized, "Needless to speak of the tracks that A R Rahman has come up with for his mentor.

From peppy to mellifluous, Rahman has belted out numbers that makes OKK a complete if not perfect romance.

[36] R. S. Prakash of Bangalore Mirror wrote, "Rahman's background score is top-notch, especially in the romantic sequences.

"[37] Shankar of Oneindia Tamil noted that the soundtrack brings a feel of happiness to the heart, rewarding the album with 3.5 stars out of 5.

[38] Sify's critic Siddharth wrote, "OK Kanmani is an album that has tracks that didn’t amalgamate imaginations.

"[40] Anamika Nair based at DNA India wrote, "The legendary duo Rahman-Ratnam...come together once again and created this magic number.

[56][57] Shashwat, Deepak, Anand, Shenbagaraj, Santosh, Maalavika, Veena, Shashwathi, Sowmya Raoh, Soundarya, Nivas, Sivakumar, Dhana, Raveena Ravi, Srinidhi