Omarosa -- I'm Engaged!!! Check Out The Rock! (PHOTO)

Omarosa gained some weight over the weekend ... with a fat rock. She's engaged!

John Allen Newman proposed to Omarosa Sunday in front of his congregation at The Sanctuary @ Calvary Church in Jacksonville, FLA ... a churchgoer who witnessed the proposal tells TMZ.

He's a pastor there ... so cross off finding a place and a minister from the to-do list.

Omarosa -- also an assistant pastor at Weller Street Baptist Church in L.A. -- met John when she was teaching at Howard University ... and we're told they've dated less than a year.

Congrats!