Adam Schefter of ESPN first reported the free-agent signing.
Still spent three years with the Bengals after they selected him in the second round of the 2012 draft. He racked up 40 total tackles, three passes defended, one forced fumble and a half-sack across 30 games before getting waived.
The 28-year-old New Jersey native also took center stage for a connection with his daughter, Leah Still, after she was diagnosed with Stage 4 neuroblastoma in 2014.
They received the Jim Valvano Award for Perseverance at the 2015 ESPY Awards, which the defensive tackle accepted with his daughter unable to make the trip.
"We could've lost faith and just let this battle with cancer get the best of us," Still said in a moving acceptance speech. "Or I could give my daughter's battle with cancer a purpose and use my platform to try to raise as much awareness as possible."
Still will likely jump right into a training camp battle with Deon Simon and Mike Pennel for playing time behind Steve McLendon along the Jets' defensive front.