Sources close to the 32-year-old Les Miserables star tell Us Weekly that Redmayne asked girlfriend Hannah Bagshawe to marry him over Memorial Day Weekend.
"He had been planning on it for awhile," the insider said. "They have a very relaxed and supportive relationship ... they seemed to have always known they were going to spend the rest of their lives together."
The My Week with Marilyn actor and Bagshawe first stepped out together in 2012. The two currently live together in London. Sources close to the pair say news of their engagement comes as no surprise as Bagshawe "has been basically a part of [Redmayne's] family for years now."
Redmayne will next star in the adventure thriller Jupiter Ascending.