Keyshawn Johnson is preaching one thing to Jets fans with Aaron Glenn taking the reins as Gang Green’s newest head coach.

Patience.

Johnson and Glenn were teammates on the Jets in the late 1990s and later on the Cowboys, as the two played under legendary head coach Bill Parcells.

While it remains to be seen if Glenn can reach the heights that Parcells did in his head coaching career, Johnson believes the Jets’ newest bench boss has the tools to be a successful leader, but success might not come overnight.

Jets fans have been starved for any semblance of postseason play with the longest drought in major North American sports.

But Johnson said supporters need to stick with Glenn as he builds things his way.

“I would say to [Jets fans], you got a good one. Don’t f–k it up. You got a good one. You really got a good one,” Johnson told The Post’s Steve Serby.

“Don’t be in a rush to win a Super Bowl tomorrow. The Detroit Lions built their program to where they are. Buffalo built their program to where they are. It doesn’t happen overnight.” 

Glenn, a three-time Pro Bowl defensive back with the Jets as a player, was part of that transformation with head coach Dan Campbell in Detroit, which started in a not-so-smooth fashion.

The Lions finished 3-13 in Campbell’s first year — also the first season for Glenn as a defensive coordinator — before they rattled off three straight winning seasons, including this year’s 15-win campaign, a franchise record.

Johnson believes that Glenn has what it takes to make the leap from overseeing the defense in Detroit to the entire football team in New York.

Part of that has to do with Glenn’s personality.

“Absolutely,” Johnson said. “100 percent. We’re not talking about Todd Bowles here. That’s quiet. He says very little. Aaron Glenn says a lot. Aaron Glenn will chew you out. He doesn’t mind chewing people out.”