Ann Myatt has apologised for her "ill-judged" comments which left Labour's Tracy Brabin, a friend of Mrs Cox, visibly shocked and members of the audience gasping and groaning.
Mother-of-two Mrs Cox, 41, was shot and stabbed by neo-Nazi Thomas Mair in her Batley and Spen constituency just days before last year's EU referendum.
Ms Myatt, in a statement, said: "I wholeheartedly apologise for my ill-judged remarks at the hustings and for any offence they caused. I said sorry at the time and would like to apologise again for my comments, which were out of character and came at the end of a tiring day."
A video of the hustings shows Ms Myatt addressing integration and saying: "This sort of evening is absolutely first-rate because we have here people of all faiths, we have here people from different parts of the community and we've not yet shot anybody so that's wonderful."
Former Coronation Street star Ms Brabin is seeking re-election after replacing Mrs Cox following a by-election last year.
Labour's national election coordinator Andrew Gwynne said: "These remarks are appalling. That they come from the Conservative candidate beggars belief."
He said Conservative leader Theresa May's campaign should also "immediately apologise".