Considered as one of the most talented left-arm spinners in the country, Ojha first came into limelight when he ended up among the top ten bowlers in the league stage of the 2006-07 Ranji Trophy season (just his second season) with 29 wickets at an average of 19.89 in six games for Hyderabad. Consistent performances thereafter, for India A, helped him bag an Indian T20 League contract with Hyderabad and he soon turned out to be a successful product of the league and emerged as the bowling star for Hyderabad, with the acquisition of a 'purple cap' in the third season.

After a decent outing in the first season of the Indian T20 League, Ojha got a deserved call-up to the ODI side in the 2008 Asia Cup, against Bangladesh. In a spree of appearances, Ojha displayed reliable bowling acumen with economical spells and regular wickets. It was enough to win a place in India's 2009 World T20 campaign, which he commenced in style with a noteworthy Man of the Match effort of 4/21 against Bangladesh. Later that year, Ojha received a maiden Test call-up against Sri Lanka in Kanpur and bowled decently. Gradually, he began to form a formidable spin force with Ravichandran Ashwin and the lethal pair wreaked havoc on the subcontinental pitches.

Ojha however, remained a second choice spinner to Ashwin outside the subcontinent. He signed for the county side Surrey in 2011 and played a crucial role in Surrey's promotion to Division One of the LV County Championship. His success continued in 2012 when he was picked by the Mumbai franchise for the fifth season of the Indian T20 League. Ojha rates his Man of the Match performance in Sachin Tendulkar's farewell Test In Mumbai as one of his most cherished memories.