Harrison bounced around the league last season, appearing in 17 total games with the Memphis Grizzlies, Cleveland Cavaliers and New Orleans Pelicans. He averaged 3.2 points and 1.4 assists per game combined for the three organizations.
He finished the year in the EuroLeague after signing with Russia's BC Khimki in February.
The 24-year-old now has a chance to work his way back to the NBA with the Warriors, a squad that can use depth at guard after losing reserves Shaun Livingston and Andre Iguadala this offseason. Klay Thompson will also be out to start the year after suffering a torn ACL.
Harrison will likely compete with Alec Burks and Jacob Evans for playing time at point guard behind Stephen Curry and D'Angelo Russell.
Despite Harrison's recent struggles, the Kentucky product averaged 9.5 points and 3.2 assists per game with Memphis in 2017-18, starting 46 of 56 games. This experience and production could be enough to make the Warriors roster for 2019-20.