The 6-foot-11, 240-pound Jackson can play power forward or center for the Grizzlies. Memphis had several potential trade partners leading into Thursday, but sources told ESPN's Adrian Wojnarowski in the hour before the draft that Jackson had grown comfortable with the prospect of Memphis taking him and provided team officials with the requisite personal information they requested.
The fourth pick was the highest for the Memphis franchise since picking Hasheem Thabeet with the second overall pick in 2009. The previous time the Grizzlies had the fourth overall pick was in 2007 when they chose point guard Mike Conley from Ohio State.
Owner Robert Pera predicted last week that with the right pick -- someone to complement Conley and Gasol -- Memphis could consider a 50-win season.
"Now, I'm a Memphis Grizzly," Jackson told ESPN after the selection. "That's crazy. I'm really happy. I'm so happy."
Jackson was joined at the draft by his parents, mother Teri and father Jaren Sr., who played 13 seasons and also coached in the NBA.
"He loves me. He's been my coach, my mentor, my father, and my mother's been with me every step of the way," Jaren Jr. told ESPN after being picked.
The Grizzlies also had the 32nd overall pick in the second round.
Conley gave a thumb's up to Jackson's selection on Twitter.
Jackson proved in his first season in college he has the ability to be a game-changer, averaging 10.9 points and 5.8 rebounds. He also shot 39.6 percent from 3-point range and blocked 106 shots, a single-season record at Michigan State.
As the youngest player in the draft at 18 years, 7 months, Jackson might have the highest ceiling in terms of his ability to affect the game on both ends of the floor. He has enviable physical tools, including a 7-foot-4 wingspan and tremendous mobility.
Jackson's ability to space the floor (40 percent from 3-point range and 80 percent from the line), block shots (5.7 per 40 minutes), switch on every screen and, increasingly, put the ball on the floor from the perimeter makes him an ideal fit for the modern NBA.
Jackson joins a franchise coming off its worst season in almost a decade. The Grizzlies recently reshaped their coaching staff, with J.B. Bickerstaff ultimately succeeding David Fizdale, who was fired in late November. Last month, the team named Jerry Stackhouse, Nick Van Exel and six others as assistants.
Bickerstaff said his coaches would emphasize "discipline, grit, physical and mental toughness."
Information from The Associated Press was included in this report.