The 34-year-old former glamour model, who has announced she is pregnant again, was due to join friend Duncan James from boy band Blue on the C5 show, reported Sun online.
Her spokesman last night confirmed that she would not be taking part and insisted she has taken the step because she could not fit the filming into her schedule.
"Katie was not confirmed for Celebrity Wedding Planner because the dates wouldn't work for her diary," her spokesman said.
C5 will announce the line-up for the new series shortly and it was reported that bosses want her to be on the show.