Same-sex weddings were made legal in May of this year, however, Proposition 8 is seeking to make marriage as between a man and a woman only under the constitution of the US state.
Opinion polls have shown a swing in the number of people in California who are against gay marriage.
DeGeneres’ television advert is going to get shown in the run-up to the California state ballot on 4 November.
The opposition to legal marriage for gay people are doing their own publicity campaign too, and they are claiming that children will be get taught about such weddings as part of their education.
DeGeneres came out of the closet back in 1997 on the sitcom Ellen, which is named after her.
