The 59-year-old announced the news just before the reunited group took the stage at Strathallan Castle in Perthshire.
"Hi All...just to say TITP is my last gig," he wrote on his Facebook page. "Disappointed is an understatement... Details will follow in due course..."
He returned to social media on Sunday (10Jul16) to dismiss rumours suggesting his health was behind his exit from the Bye Bye Baby hitmakers.
The band has confirmed Wood’s exit on Twitter, writing: "He played a blinder... It was definitely an emotional night!"
Wood, Les Mckeown and bassist Alan Longmuir reunited the band in December (15).
It is not clear if MCKeown and Longmuir will continue with the reunion plans, which was slated to include tour dates in Japan and the U.S. in 2017.
Saturday's T In The Park festival appearance was a real treat for fans as the band ran through a string of hits and singer MCKeown revealed their song Saturday Night was beloved by punk icons The Ramones.
"The Bay City Rollers were very popular with a band called The Ramones," he told the crowd. "They wanted to copy The Bay City Rollers, believe it or not... This is the song that inspired them!"