West, 36, pulled off a huge birthday surprise by renting out an entire baseball stadium and asking Kim to marry him, reported E! online.
The rapper borrowed AT&T Park, home of the San Francisco Giants, and popped the question in front of family and friends.
"He projected 'Please marry me' onto the stadium screen for everyone to see," a source said.
After years of friendship, Kim and West began dating in April 2012 and welcomed baby North on June 15. The socialite was previously married to NBA player, Kris Humphries.