The 50-year-old was said to be tying the knot with make-up artist Mezhgan Hussainy in four locations around the world after their whirlwind romance.
But he said: "In spite of various people claiming to be making arrangements for our wedding, no such plans exist. When Mezhgan and myself decide the time is right, we will make our own plans."
The star added: "I just want to clarify the situation because I keep reading about different people planning our wedding."
Simon's spokesman also denied that the TV talent judge, who is launching the US version of The X Factor, had decided to pull out of the Britain's Got Talent auditions next year.
Max Clifford said: "I spoke to Simon and absolutely no decision has been made. He's absolutely committed to it and won't be making a decision as to his appearances until the end of June, when he's back in the country."