Jonathan Owens had full control of Simone Biles' flames on Halloween ... grabbing a handful of his future wife in some steamy fireman-costumed pics!!
The Olympic gold medalist shared the hot photos on Sunday ... showing the Houston Texans safety getting a little handsy for the October holiday.
Biles was rockin' a 2-piece 'fit with flames all over it ... while Owens -- wearing fireman overalls and an FD cap -- made sure the blaze didn't get too out of control.
Biles asked her 6 million IG followers to give the sexy post a caption ... and one fan obliged, writing, "I don't think he wants to put that fire out. He just wants to tame it. 🔥🔥🔥🔥🔥"
Another person said, "Costumes 🔥. Baby Im on fire, come water me down. 😍" while someone else called Owens the "luckiest firefighter ever."
This is the couple's first Halloween together as future husband and wife ... Owens just proposed to the gymnast with a 3-carat oval diamond ring in February after two years of dating.
Seems they've got the whole couples costume thing down pat ... can't wait the 365 days to see the next one!