Britain, the United States and France hit targets in Syria Saturday in response to a reported chemical attack in Douma.
Parliament returns Monday after a spring break, and was not consulted about the action. The government is not legally bound to seek Parliament's approval for military strikes, though it is customary to do so.
May plans to tell lawmakers that the airstrikes were "in Britain's national interest" in that there was broad international support to help prevent further suffering from chemical weapons attacks.
The government says it will seek an emergency parliamentary debate on the airstrikes Monday, though that is unlikely to satisfy angry opposition lawmakers.