Hart was supposed to tape his interview for the programme, which debuts on Monday, September 9, earlier this week, but his weekend car crash forced him to pull out of the appearance - and his "Jumanji: Welcome to the Jungle" pal stepped in at the last minute.
"Because Kevin couldn't be here, one of his good friends stepped the heck up and I love him," Kelly explains in a teaser for her new show. "I got real nervous for my first show. I was like, 'I am so sorry you're sick'... I was calling all my friends."
"He (Johnson) left his honeymoon to come here... His wife probably hates me... to come and take Kevin's place."
Johnson insists he had a blast as Kelly's first guest, tweeting, "When my son @KevinHart4real goes down with an injury, his big daddy steps in. I did leave my honeymoon early (Lauren approved cos she LOVES Kelly) and now me and Kelly are new best friends. Tune in this Monday! We had the best time! #greathost #hotcrowd#amazingenergy."
Johnson recently tied the knot in Hawaii with his longtime girlfriend Lauren Hashian, while Hart is recovering from back surgery following his scary crash in California on Sunday morning.