Welcoming the confirmation, Munster head coach Rob Penney said: "It's indeed good news that two quality sides such as Gloucester and London Irish will be part of our build-up to the new season. Both are quality outfits and will provide us with the ideal preparation to our season."
Munster, meanwhile, also announced that Danny Barnes has agreed a two-year deal with English club Newcastle Falcons.
The 23-year-old back, who has been capped 34 times by the province, is looking to gain experience and has not ruled out a return to Munster sometime in the future.
"It wasn't by any means an easy decision for me to move, because I'm a Munsterman and always will be," said Barnes.
"But I feel I need to be playing as often as possible at the highest level I possibly can and after discussion with Rob (Penney) and Garrett Fitzgerald, we agreed that this move would benefit that ambition.
"I am grateful for their support and encouragement and though I intend applying myself fully to Newcastle Falcons, I will harbour thoughts of returning to Munster at some stage in the future if the opportunity arises."
Penney commented: "Given the composition Munster squad currently, we understand Danny's reasons for looking to play elsewhere.
"Danny has been a very valued member of the Munster squad and contributed a great deal during his time here. We collectively believe that it's in his own best interests to move to Newcastle Falcons where he can further develop his talent.
"He leaves with our very best wishes and we don't rule out the possibility of him donning the Munster red in the future."