The actor popped the question while filming war movie Red Tails on location, after the Colombian actress jetted over to Europe to visit him.
Although he has never confirmed his relationship with Henao, the pair has been spotted together at showbiz events and they were snapped frolicking in the sea together during a vacation in December 2007.
And when WENN.Com bumped into the couple partying at a bar in Prague on Friday night, he confirmed, "I just got engaged".
Howard, 40, hooked up with Henao after splitting with ex-wife Lori McCommas for the second time in 2005.
Howard and McCommas ended their 14-year marriage in 2003, but he successfully wooed her back and they remarried, only to split for good soon after.
Just last year the actor revealed how he had bought McCommas her childhood home and stalked her in a bid to win her back.
But, after their second split, he moved on and found love with Henao, who helped him recover from the heartbreaking death of his beloved mother Anita to cancer last September.
The couple can be seen together in 2009 movie Fighting.