It emerged on Thursday that wicketkeeper-batsman Saha, who provides cover for skipper MS Dhoni and has yet to feature on the tour, had picked up an unspecified injury.
Saha's misfortune has opened the door for Ojha, uncapped in the longest format of the game, to act as understudy with two Tests remaining in the five-match series.
"Wriddhiman Saha has been ruled out of the remainder of the ongoing Test series between India and England, due to injury," a brief statement on the Board of Control for Cricket in India's official website read.
"The All-India Senior Selection Committee has picked Naman Ojha as his replacement. Ojha will join the squad at the earliest."
It represents Ojha's maiden call-up to the Test squad, as the 31-year-old gets his reward for showing superb form during India A's tour of Australia earlier this month in which he recorded two centuries and a double hundred in a two matches against Australia A.
The five-Test series is level at 1-1 with two matches remaining after England completed a 266-run thumping of the tourists at the Ageas Bowl in Hampshire on Thursday.
The fourth match of the series gets under way at Old Trafford next Thursday, with the final Test at the Oval starting on August 15.