30-year-old Karen Wolfendale from Bolton is raising money for the Guide Dogs for the Blind Association.
She will ride in the front seat of one of the trains wearing a novelty dog suit on Sunday.
Karen told the Bolton News: “I have always loved rollercoasters so I think this is a fantastic opportunity to something a bit different and have some fun whilst raising vital funds for the charity.
“I have not been on this rollercoaster before. I am a fan of rides, but I might not be by the end of the challenge.
“I am wearing the dog suit to attract a bit of attention and hope it will encourage people to donate because it is a great charity.”
The Ultimate is located at Lightwater Valley in North Yorkshire and is one of the most physically aggressive rollercoasters in the country.
It opened in 1991 and its 1.5-mile track was for ten years the longest of any rollercoaster in the world.