He made his international debut for Wales in 2005 with a try during a record 77-3 victory over the USA and reached the semi-finals in the final two legs of the IRB World Sevens series in 2007.
"I'm really excited about signing with the Dragons region for next season and am looking forward to playing regular rugby and helping to bring success alongside an exciting squad that is being built at Rodney Parade," said Selley.
"It's been a happy ground for me, having scored tries on my visits to Rodney Parade over the years, and I hope to score many more as it becomes my home ground."
Tal Selley will become the first player to play for all four regions when he joins the Dragons squad next season. Dragons Head Coach Paul Turner is hopeful that he will become a mainstay with the region for next year and beyond.
He said: "Tal is a fine talent and a positive signing for the region next year. In his ability to score tries as well as his pace, he is a rare commodity.
"I've followed Tal on the Sevens circuit for a number of years and believe that any player with the ability to score tries as he has in the IRB Sevens Series is an excellent prospect for the region."