Academy winger Simon Zebo, who turns 21 today, and the 22-year-old out-half Declan Cusack have agreed two and one-year deals respectively.
Since making his debut in August 1998, lock O'Driscoll has played 181 competitive games for Munster, with his provincial career punctuated by a two-season stint with Perpignan.
He captained Munster in most of their games on their way to the Magners League title in 2009 and led the side that was narrowly beaten that season by New Zealand.
Commenting on the news, Munster head coach Tony McGahan said: "We're delighted to continue signing key players to the rugby programme and this quartet, at opposite ends of the spectrum, is no different.
"To have senior players such as Mick and James, who individually have been playing consistent high level rugby this season and who play such an important part in the Magners League and Heineken Cup especially when the Internationals are away, balances the signing of young up and comers like Simon and Declan.
"Simon has continued to gather game-time recently after making his debut last season. He brings a genuine attacking threat to the backs division and we look for him to continue his development with the senior programme for the rest of the season.
"Declan's progress in the last twelve months since his debut last season was evident in his first start of this season when he played an important role in the bonus point victory over the Dragons.
"What turned out to be a long term injury in the pre-season plus the presence of quality players such as Ronan O'Gara and Paul Warwick have curtailed his appearances, but the future looks promising for Declan who it must be remembered was a late starter to professional rugby."