P. Unnikrishnan is a Carnatic vocalist and a national award-winning playback singer. Unnikrishnan was initiated into Carnatic Music at age of 12 by Seshadri, Unnikrishnan. He was inspired by Sangita Kalanidhi Dr. S. Ramanathan. He attended a special workshop for six months on "Veena Dhanammal Bhani" under Sangeetha Kalanidhi T.Brinda and Sangeetha Kalanidhi Dr.T.Vishwa Nathan.
He is a national award-winning playback singer for his debut film songs "Ennavale Adi Ennavale" and "Uyirum Neeye". These songs were composed by A. R. Rahman, with whom Unni Krishnan gave most of his memorable songs.
Unnikrishnan is also becoming known for his experimental work. In 2008, he presented a novel jazz concert in Thiruvananthapuram with the Eli Yamin Jazz Quartet and pianist Anil Srinivasan.