The 82-year-old actor revealed in his upcoming memoir, One Helluva Ride, that the pair fell head over heels for each other when they shot the 1984 adventure-comedy film, Romancing the Stone, in Mexico while he was separated from his then-wife Diandra Douglas, with whom he has 47-year-old son, Cameron.
Turner, 72, told People: "Good heavens, what a fuss about something 40 years ago!
"I love Michael, and I look forward to enjoying the book."
In an extract from his memoir One Helluva Ride shared by People magazine, the two-time Oscar winner admitted that he and Turner lied about the truth of their love affair for the past 40 years.
"The chemistry I had with Kathleen Turner was so strong, audiences have been certain for years that we were in a relationship together while making the film," Douglas wrote.
"We both denied it through Romancing the Stone, Jewel of the Nile, War of the Roses, and even while doing press a few years ago for The Kominsky Method.
"The official story went as follows: yes, we confessed, we had amazing chemistry. Yes, we were both, as Kathleen said, 'terrible flirts', and yes, we were both tempted, but nothing ever happened between us.
"That was a lie."
The Basic Instinct alum explained that the lie was "meant to protect my wife and son", and they "told the world for 40 years".
"Kathleen and I never hit a rough spot. We found each other first as friends, then as co-stars, and finally as lovers," he said.
"Following an exhausting day of shooting in the jungle, we'd go out and have a meal, or head out with the group and afterward I would sneak into her hotel room after everybody was asleep.
"There were no cameras in elevators, no assistants using cell phones to take pictures."
They did not tell their cast mates or director Robert Zemeckis, but the "magic spell of the set" was broken when his wife and their son Cameron came to visit the set in Mexico and she "grew suspicious".
"After that visit, Kathleen and I ended things, and I went back to Diandra. I did it for Cameron, but we shouldn't have gotten back together. After that first split it was never the same between us ever again."
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