The Mavericks didn't reveal contract terms in their announcement Thursday night.
ESPN reported Harris got a $16.5 million, four-year deal.
Harris played for Dallas on a one-year, $3 million deal last season. He originally had a $9 million, three-year deal, but that was scuttled by a toe injury that forced him to miss the first half of the season
The 31-year-old Harris averaged 7.9 points, 4.5 assists and 20.5 minutes in 40 regular-season games after returning from the injury.
Acquired by the Mavericks as the No. 5 overall pick in a draft-night trade in 2004, Harris was sent to New Jersey in a trade that brought Jason Kidd to the Mavericks in 2008. Harris also played in Utah and Atlanta.