Gore, who turns 37 on May 14, will be reunited with Jets head coach Adam Gase in New York. Gase coached Gore with the Miami Dolphins in 2018, and they were together when Gase was a low-level assistant with the San Francisco 49ers in 2008.
Gore, the third-leading rusher in league history, is expected to serve as the No. 2 back behind Le'Veon Bell. Last week, Gase told ESPN that he wanted to "lessen the load" on Bell, who recorded 311 touches last season.
"I've heard [the news] from a bunch of people. He's a guy with a great work ethic," Darnold said. "He's a really good leader, a really good locker room guy, and obviously, it looks like he can still play. We're thrilled to have him. I know coach Gase has worked with him before and he thinks highly of him as well."
Gore is entering his 16th season in the NFL. He played for the Buffalo Bills last year, finishing with 599 rushing yards and 3.6 yards per carry.
The five-time Pro Bowl selection passed Barry Sanders on the NFL's career rushing list in 2019, ending the year with 15,347 rushing yards. Gore trails only Emmitt Smith and Walter Payton on the all-time list.
Meanwhile, the Jets placed wide receivers Quincy Enunwa and Josh Bellamy on the physically unable to perform list Tuesday. The franchise also waived defensive end Charles Tapper, running back Jalin Moore, cornerback Kyron Brown and receiver Keon Hatcher.
Enunwa, 27, played only one game last season because of a neck injury. Now, he will miss the entire 2020 season and his NFL career could be over.