Welch, 24, came through the Warrington academy, making a solitary appearance for the Wolves back in 2008, before moving to the USA.
He said: “There were a few options out there after the World Cup but Oxford really caught my eye. Luckily my good mate and old team mate Alex Thompson played here last season. I really respect his opinion and he sold the idea of Oxford to me. After speaking with Tony, it just felt like the right place to be. I can’t wait to get involved and start the season.”
Dallas-born Welch played for New York Raiders of the American National Rugby League, and also for the Chicago Griffins rugby union team during his time in the States.
“He is a really good kicker and has a fantastic kick return too. He’s physically strong and quick and has the experience we are looking for to take us to another level. He also has good ball skills which will benefit us on our big pitch at Iffley Road.”