Saleh was 20-36 as coach of the Jets, who are trying to snap the NFL's longest active playoff drought at 13 seasons.
Defensive coordinator Jeff Ulbrich will act as the interim coach, according to the person who spoke to the AP on condition of anonymity Tuesday because the Jets hadn't announced Saleh's firing.
It is the first time in owner Woody Johnson's 25-year tenure that a head coach has been fired during the season.
The surprising move came a day after Saleh said he was confident Aaron Rodgers and the Jets would be able to turn things around after losing two straight, including falling 23-17 to undefeated Minnesota on Sunday in London. Rodgers had his worst game with New York, throwing three interceptions.
"There's so much football to be played," Saleh said Monday. "There's so many things that we can get better at, and there's so many things that we can continue to build on, the things that we are doing well.
"So, I'm not panicked. Nobody in the building is panicked."
But apparently Johnson had seen enough from Saleh to make a change.
The Jets face the Buffalo Bills (3-2) on Monday night with a chance to share the AFC East lead with a victory. But instead of Saleh, it will be the 47-year-old Ulbrich leading the team on the sideline.
Ulbrich, who played linebacker for 10 seasons with San Francisco, joined the Jets as part of Saleh's initial staff in 2021. Ulbrich was an an assistant with Atlanta for six seasons before coming to New York.