Jim Salisbury of NBC Sports Philadelphia reported it's a one-year, $14 million contract.
Gregorius hit 22 home runs across his first four years in the big leagues, including time with the Cincinnati Reds, Arizona Diamondbacks and New York Yankees. He discovered his power stroke during his second season with the Yanks in 2016 and proceeded to hit 72 homers across the next three years.
His 2019 campaign got off to a late start after he underwent Tommy John surgery. He returned in June and finished the year with a mediocre .718 OPS and 16 longballs in 82 appearances.
The 29-year-old Netherlands native said in October he never found top form during the second half of the season and into the playoffs.
"Some days it's good, some days not," Gregorius told reporters about his timing.
The veteran infielder provides value based on his pop at a position where that's a limited commodity, but his lack of consistent production after his return from injury created uncertainty heading into the offseason.
Any decrease in power would be a major blow to his upside since he only owns a .313 career on-base percentage and rates as a negative defender in defensive runs saved, per FanGraphs.
Gregorius could provide a major boost for the Phillies offense if he's back to full strength and gets his timing worked out. An entire offseason in which he can focus on his game instead of recovering from injury should help him in that quest.
He should immediately slot in as the starting shortstop and hit in the middle of the Philly lineup behind Bryce Harper and Rhys Hoskins.