The hugely talented 22-year-old, comfortable playing at both full back and wing, made a total of 69 appearances for Bristol and scored 20 tries.
The former England Under-19 international joined Bristol in 2007 and scored nine tries in 19 starts in his first full season, catching the eye of the England Saxons selectors before an injury ruled him out.
Arscott again impressed in the Championship last season to finish with ten tries, including a hat-trick against Coventry in October.
Head Coach Richard Hill is delighted with his latest acquisition and the chance to once again work closely with Arscott.
"Tom is rapid and a natural try scorer. He loves scoring tries and if you give him half a chance he will take it and so we're delighted he will join us at Warriors," said Hill.
"He was one of the stars of the Championship during his time at Plymouth and when he came to Bristol he made an immediate impact in the first team. He knows the league, all the grounds we will be playing at and knows what is expected.
"Tom is an exciting young English player who is very versatile, as he can play on the wing or full back, and is very quick so will add another real potent weapon to our squad."