'Empire' Stars Trai Byers & Grace Gealey Have Secret Island Wedding

The Lyon family is gonna need another seat at the table ... because "Empire" co-stars Trai Byers and Grace Gealey tied the knot in a very real wedding.

The private ceremony and reception went down Thursday at a mansion on Grand Cayman Island ... the guest list was limited to close friends and relatives ... none of their "Empire" co-stars attended.

Guests dined in style -- steak and lobster -- and danced to hip-hop, disco and, of course, reggae.

#Congratulations