The singer will play the event, which is held on the city's Pier-Head and the Stanley Street Gay Quarter on August 4.
Collins said: "I'm so excited to be involved with Liverpool Pride, it's such an amazing event and in such a vibrant city it's bound to be an incredible celebration!
"I love the gay community and I love that I can be a big part of it, even if it's only by keeping the bars open!"
He added: "The awareness of the gay community that Liverpool Pride generates in the city makes it safer and more fun for everyone, and every year the event gets bigger and more fun. I'm honoured to be a part of it."
Zoran Blackie, chair of Liverpool Pride, said that Collins "seemed like the perfect choice" for the event, explaining: "He's doing a lot for the LGB&T community across the UK and is proving to be somewhat of a role model for younger gay people."
The star recently told Digital Spy that he is already planning his next album, where he hopes to collaborate with Sam Sparro and Jamiroquai.
Watch the music video for Marcus Collins's latest single 'Mercy' below: