The revamped BBC motoring show has suffered flagging ratings, with a new low of fewer than 2m viewers for the series finale on Sunday.
In a statement, Evans said: “I have never worked with a more committed and driven team than the team I have worked with over the last 12 months. I feel like my standing aside is the single best thing I can now do to help the cause.
“I remain a huge fan of the show, always have been, always will be.”
In a tweet to his 2.3m followers, Evans added: “Stepping down from Top Gear. Gave it my best shot but sometimes that’s not enough.”
Stepping down from Top Gear. Gave it my best shot but sometimes that's not enough. The team are beyond brilliant, I wish them all the best.— Chris Evans (@achrisevans) July 4, 2016
Full steam ahead then with Radio 2, CarFest, Children In Need, 500 Words and whatever else we can dream up in the future.— Chris Evans (@achrisevans) July 4, 2016
The motoring show has struggled to attract viewers since Evans took the wheel, replacing Jeremy Clarkson, James May and Richard Hammond, who all left the BBC after Clarkson was fired for a “fracas” with a producer.
Sunday’s finale lost out to ITV’s coverage of Euro 2016 and drew an average just of 1.9m people, according to BARB figures.
The rebooted Top Gear launched over a bank holiday weekend with 4.4m overnight viewers, but then plummeted to 2.8m for the second episode. The show never went back above that figure.
By contrast, the former Top Gear presenters, who will launch their new Amazon Prime show The Grand Tour in the autumn, bowed out with 5.8m viewers.
Despite reports of poor ratings, Evans remained defiant, claiming: “Overnight television viewing figures for Top Gear have never been less relevant.”
He wrote in June: “Top Gear audience grew throughout the hour. FACT. Won its slot. FACT. Still number one on i Player. FACT. These are THE FACTS folks.”
Evans made his debut in May as part of a seven-strong line-up of presenters. He was joined by Friends star Matt LeBlanc, racing driver Sabine Schmitz, Formula One commentator Eddie Jordan, YouTube star Chris Harris, car enthusiast Rory Reid, and The Stig.
Before the revamped show had even aired, it was already embroiled in a row over “donuts” around The Cenotaph.
After LeBlanc and racing driver Ken Block caused an uproar by performing stunts around the war memorial, Evans branded the incident “disrespectful” and said the footage would not be aired.
Evans and LeBlanc have also been forced to deny claims that they were at loggerheads during filming.
LeBlanc, 48, tweeted in March: “I’m at war with @achrisevans? That’s funny, I thought we were pals.”
Evans, 50, also laughed off the report, tweeting: “Just been on the phone to @Matt_LeBlanc to confirm we are ‘at war’ as reported in The Sun today. He says, ‘sure, whatever..’ Why I oughta !”
Mark Linsey, director of BBC Studios, said: “Chris is stepping down from his duties on Top Gear. He says he gave it his best shot doing everything he could to make the show a success.
“He firmly believes that the right people remain, on both the production team and presenting team, to take the show forward and make it the hit we want it to be.”