The pair are teaming up for the new podcast, "90210MG", launching 9 November on the iHeartRadio app - the same day that the original show debuted.
It will feature both Spelling and Garth looking back on old episodes of the show, which ran for 10 seasons between 1990 and 2000. Spelling tells People: "Fans always say to us, 'We can't believe you're actually best friends'.
"We wanted to do a girlfriends podcast and then blended it with 90210 to do it for the fans," she shared. "We have a lot to talk about. It's going to be really fun!"
Garth also added that she hasn't watched a full episode of the show, "but sometimes I'll have it on in the background on the TV when I'm cooking.
"I see all those youngsters on the TV. I remember those really important connections and friendships that we all had- and all the fun we all had," she reminisced.
"My intention is to be able to be happy and just remember," she added. "There were terrible times and really great times. But it was a really incredible 10 years. And I'm excited to look back and appreciate it all over again."
Speaking to PEOPLE, Tori shared, "Sometimes friends can come and go, but we've been friends for thirty years. We've gone through decades of change as women, we're moms now and it's really the one relationship that has stayed all this time!'
She added, "Fans always say to us, 'We can't believe you're actually best friends.' We wanted to do a girlfriends podcast and then blended it with 90210 to do it for the fans. We have a lot to talk about. It's going to be really fun!"