Caro, 21, scored four tries in 12 appearances for London last season, and was crowned rugby league’s fastest man at the Nines finals night at Headingley in June.
His move north has finally been confirmed by the Robins, on a two-year deal.
Caro said: “I had one or two options but once I’d spoken with Craig (Sandercock) it was a no-brainer for me.
“He has a reputation for developing younger players and I’m keen to work with him. Obviously I’m sad to leave London as I’ve my whole playing career has been with the Broncos and I’ve lived down there all my life. But this is a great opportunity for me and I didn’t want to let it slip by.
“I’ll always be grateful to the Broncos as they gave me my chance in rugby league and I leave there having made a lot of friends. I’ve also got plenty of good memories, the most special one probably being my debut against Salford. Signing for Hull KR is the start of the next chapter in my career and I’m really excited and can’t wait to get started in pre-season.”
Hull KR head coach Craig Sandercock said: “Omari fits the profile of the type of the player we want to bring into the club. At 21-years-old he’s still in the early stages of his career and someone that we believe will get better and better. Obviously he has real pace but there’s a lot more to his game than that and when I met him I was impressed with his eagerness to learn and knowledge of the game.
“We’re looking forward to having him on board at the club and I know that he’s raring to go.”