The pair are among Bachelor/Bachelorette stars who will compete for a second chance at love and the $500,000 prize, according to Entertainment Weekly.
Pavelka and Girardi became engaged on the 14th season finale of the ABC romance show, but confirmed their separation later that year.
Girardi is not the only woman from Pavelka's season of The Bachelor to make the cut. She will be joined by Gia Allemand, who appeared on the debut season of Bachelor Pad and was recently rumoured to be romancing Pavelka.
Ella Nolan, who was cut following a double date with Jake, will also take part on the sophomore season of the summer series.
Girardi's boyfriend Kasey Kahl, who fought for Ali Fedotowsky's affections on the sixth season of The Bachelorette, has also been cast. The couple are reported to have begun dating earlier this year after meeting while working together on a charity project.
Other bachelors from Ali's season who will appear include Kirk DeWindt and Justin 'Rated R' Rego, who left the show after Ali confronted him about speculation that he had a girlfriend back home.
Former couple Holly Durst, who appeared on The Bachelor's 12th season with Matt Grant, and Michael Stagliano, who tried to woo Jillian Harris on The Bachelorette, will also compete for the prize.
Other contestants include three unknown men from the current season of The Bachelorette starring Ashley Hebert, and four women from Brad Womack's recent stint as The Bachelor: Michelle Money, Jackie Gordon, Melissa Schreiber and Alli Travis.
Erica Rose, who appeared on Lorenzo Borghese's The Bachelor and Graham Bunn from DeAnna Pappas's The Bachelorette have also been cast.
Bachelor Pad debuted on ABC last year. The first season was won by Natalie Getz and David Good, who triumphed over Tenley Molzahn and Kiptyn Locke. Elizabeth Kitt and Jesse Kovacs were placed third.
Bachelor Pad premieres Monday, August 8 at 8/7c on ABC.