The contract is worth $28 million, per The Athletic's Ken Rosenthal.
Gregorius enjoyed a bounce-back season in his first year with the Phillies in 2020, slashing .284/.339/.488 with 10 home runs. He suited up in all 60 of Philadelphia's games during the pandemic-shortened campaign.
Locking up Gregorius marks the second major free-agent move by the Phillies this week. Superstar catcher J.T. Realmuto officially signed a five-year, $115.5-million contract on Friday.
The move also continues to thin out the free-agent infield market, which has seen Marcus Semien (Toronto), Andrelton Simmons (Minnesota), Kike Hernandez (Boston) and Jurickson Profar (San Diego) sign in recent days.