The Pop Idol runner-up will set sail on the P&O ship to Bruges next month. He will join the cruise when it leaves Southampton on September 3.
Gates will perform a selection of his tracks including 'Stupid Mistake' and 'Sunshine' in front of up to 2,000 passengers, as well as signing autographs and speaking to fans after the show.
"I'm really excited about performing on board Oceana, I've never been on a cruise ship before but I've always wanted to, and so this is going to be a fantastic experience for me," Gates said.
P&O Cruises managing director Carol Marlow said: "Entertainment is one of the key elements of any cruise holiday and we are proud of our vast range of entertainment and guest appearances.
"Gareth is a worldwide pop star and we are very excited to have him perform on board Oceana. We are sure he will be a great hit with passengers on this weekend cruise."
Gates said in early 2009 that he had no plans to record a new album after securing the lead role in the West End version of Joseph and the Amazing Technicolour Dreamcoat.
Watch the video for 'Sunshine' by Gareth Gates below: