The signings were completed just in time for camp, which starts Tuesday. The rookie contract talks took longer than usual because the team had tried the unconventional strategy of including performance bonuses in their deals to avoid guaranteeing the maximum salary allowable.
Henry was the 12th overall pick in the June draft and Vasquez was taken 28th. Both signed multiyear deals, additional terms were not disclosed.
Teams can pay players up to 120 percent of their scale amount, which this season is about $1.7 million for the No. 12 pick. The Grizzlies had wanted to tie the 20 percent to bonuses but eventually relented.
Grizzlies general manager Chris Wallace previously acknowledged that performance bonuses were not something the Grizzlies have offered in the past, but noted other teams have put some bonuses in from time to time and the team decided to adopt the practice this year.
"It's great to have both Xavier and Greivis signed and in the fold now," Wallace said in a team statement announcing the signings. "They're both very bright young men from tremendous college programs. We think they can definitely help our team."
Henry is an athletic 6-foot-6 shooting guard who played college ball at Kansas. He's expected to help the team improve its perimeter shooting, which was a problem for the Grizzlies last season. Memphis finished 30th in the NBA in 3-point shots made and attempted, and 26th in 3-point field goal percentage.
Henry said he tried to stay positive during the contract negotiations.
"I wasn't really thinking about it too much," Henry said in a statement released by a team spokesman. "It was really between my agent and (Grizzlies owner) Michael Heisley. I was just worried about working out and he would give me little updates on how the contract was going.
"I was always just enthusiastic about it. I was just waiting for it to get done because I figured it could get done at any time."
Vasquez, a gritty 6-foot-6 point guard who was the Atlantic Coast Conference player of the year at Maryland last season, adds depth behind expected starter Mike Conley. Vazquez injured his right ankle while playing in the NBA Summer League in Las Vegas and had surgery in late July to remove a bone spur.
Vasquez has been working to get healthy and says his ankle feels good. He said he expects to be 100 percent and back on the court in two or three weeks.
"I can't work out with the team yet but just watching, learning plays and all that stuff," Vasquez said. "I have no words to describe how happy I am right now. I'm very excited."
Heisley has said he expects the team to make the playoffs this season. Last season, the Grizzlies fell short of their first .500 season since 2006 and posted the second best improvement in wins behind Oklahoma City.