In an Instagram post shared Sunday night, the 32-year-old smooched Reid as a brand new, brilliant square-cut diamond dazzled on her ring finger.
"Memories forever!!! #thelochtes #LA" Lochte wrote.
Reid, a Playboy model, also posted the pic to her own Instagram, writing "Speechless. Absolutely beautiful. So in love with YOU."
The couple's engagement comes right in the middle of Lochte's Dancing With the Stars stint, for which he has regular rehearsals with partner Cheryl Burke. During the competition's premiere in September, two men jumped on stage to protest Lochte's appearance. Those men have since been charged with misdemeanors.
Congrats to the happy couple!