The Maggie May singer - who cancelled a number of concerts earlier this month due to health reasons - appeared unwell and was doubled over in pain while performing at the Utah First Credit Union Amphitheatre in West Valley City, Utah, on Friday.
Video footage shared by TMZ showed the 81-year-old star leaning on a piano and grabbing other parts of the set for support during Young Turks before staff came out with an oxygen tank.
Stewart later told the crowd he had almost fainted and made a few jokes, before finishing the show sitting in a chair.
The Hot Legs hitmaker previously cancelled his May 29 and 30 The Encore Shows residency gigs at The Colosseum at Caesars Palace in Las Vegas at the last minute after a vocal rest order from doctors.
"My apologies to my family of fans. I am on vocal rest as I recover from a sinus infection. I look forward to seeing you at a future show at Caesars Palace or on tour this summer," Stewart said.
And on June 12, he cancelled his show in California just hours before it was due to start after contracting laryngitis.
A statement on his Instagram Story at the time read: "Rod Stewart very regretfully has had to cancel his show tonight in Chula Vista, California.
"He travelled to the venue and made every effort to perform, but on the advice of his doctor, and following a diagnosis of an acute upper respiratory infection, that has resulted in laryngitis, he is unable to take the stage this evening."
In another slide, Rod posted a shot of himself on the empty venue's stage as he apologised to his disappointed fans for the show's cancellation.
He wrote in a third story: "Following treatment, I'm feeling much better, but my voice is not.
"I'm very disappointed and sincerely apologise for any inconvenience to my fans. I did everything I could to make the show happen tonight, but, unfortunately, it just wasn't possible.
"I will do my utmost to reschedule. Rod."
However, Stewart then faced a backlash when he posted a video of himself and sons Liam, 31, and Alistair, 20, flying to Boston in a private jet to watch his beloved Scotland take on Haiti in the World Cup.
He said in the video: "Here we are flying off to Boston to see Scotland in the World Cup.
"It's been 28 years so these kids, I've told them about it, but they've never been. I've been to seven World Cups."
But in the comments section people were quick to slam Stewart for making the trip despite his illness and subsequent show cancellation.
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