After picking up the guitar at the age of 5, Mendonsa went on to play rhythm guitar in a few local bands with friends Siddharth Coutto (drums) and Girish 'Bobby' Talwar (rhythm guitar, bass). Sometime around 1997-98, they formed Zero, with Rajeev Talwar on vocals.
Over the years, Zero grew to enjoy nationwide popularity in India. With Warren, Zero released two albums and an EP - Albummed (1999), Hook EP (2002), & Procrastination (2005).
Besides his work in Zero, Warren Mendonsa recorded & released numerous instrumentals - the most popular works being Christmas in July, Spitleaf, & Evil- which enjoyed some fame on online music forums like Gigpad, & Harmony Central. He was also involved in many online collaborations with musicians - most notably Adam Martin, Ed DeGenaro and Zorran Mendonsa - which resulted in a few songs. In late 2004, Mendonsa moved to Auckland, New Zealand, thereby quitting Zero.
During this period, he was also a highly sought-after recording engineer and session guitarist in Bombay, having worked on various film soundtracks, advertising jingles, & other albums.
After moving to Auckland, Warren Mendonsa began to work on solo instrumental material. While visiting India, he reunited with Zero for a few gigs, most notably at the Great Indian Rock Festival 2006.