The Britain's Got Talent hosts said that they would give the music mogul the "night of his life" before his marriage to Mezhgan Hussainy.
Declan Donnelly, 34, told TV Biz: "We'd take him around London I think - and he'd have to end up handcuffed to a lamppost somewhere."
He added that Cowell, 50, would not be taken to a strip club as part of the event, joking: "He goes to them most weekends anyway!"
Ant McPartlin, 34, added that he and Dec would be disappointed if they weren't involved in some way. Cowell's brother Tony recently claimed that four ceremonies are planned - with nuptials apparently taking place in Brighton, LA, Barbados and Hollywood.