The couple, who got engaged last year, were rumoured to have married on Saturday at a private estate in Jackson Hole, Wyoming.
But a source tells Us Magazine Justin wasn't even in Wyoming on Saturday. He was in Puerto Rico filming his new movie Runner, Runner. He was even spotted by another witness going to the cinema with friends on Saturday afternoon.
Meanwhile Gossip Cop claims to have spoken to one of Timberlake's relatives, who says the reported "secret ceremony" never happened.
Gossip blogger Janet Charlton started the rumours on Friday.
"A source just told us that Justin Timberlake and Jessica Biel are getting married in Jackson Hole, Wyoming as we write this! They pulled a fast one on everybody! They are in the middle of their ceremony at a very fancy private estate and members of the wedding party are staying at the Four Seasons Hotel there."
The next day she updated her blog: "Last night turned out to be the rehearsal dinner and the wedding is actually today."
Adding to the rumour, celebrity wedding cake designer Sylvia Weinstock tweeted at the weekend that she was enjoying the sites in Jackson Hole.
And gossip site pinkisthenewblog.com claimed that a stage had been built over the last two weeks at the ranch of one of Justin's friends.
Jessica and Justin are yet to comment on the rumours.