Henderson, 28, averaged 8.7 points and 2.9 rebounds off the Trail Blazers' bench last season. His role in Portland likely will be filled by Evan Turner, who agreed to a contract with the Trail Blazers on the first day of free agency.
It will be a homecoming for Henderson, who played high school basketball in the Philadelphia area at Episcopal Academy. His father, Gerald Henderson Sr., also played for the 76ers, in 134 games during the 1987-88 and '88-89 seasons as part of his 13-year NBA career.
He is considered a good wing defender and was the elder statesman in a young Portland team's rotation after arriving in an offseason trade from the Charlotte Hornets.
The 12th overall pick in the 2009 draft, Henderson was primarily a starter during his six-year stint in Charlotte.
He has career averages of 11.5 points and 3.3 rebounds per game.
ESPN.com's Tim MacMahon contributed to this report.