The evening will also feature sneak peeks of season two, a new musical number performed by Rodrigo and Bassett, special messages from and fun facts about the cast, fan favorite "Buspool Karaoke" music videos and much more.
In celebration of season one's success, the cast shared some of their favorite memories, including the homecoming episode and a spontaneous dance party launched by Bassett.
“For everyone who was there at the birth of 'High School Musical' on Disney Channel 15 years ago, this is like a homecoming!" Gary Marsh, president and chief creative officer, Disney Branded Television, said in a press statement. "And whether you’ll be experiencing the new series for the very first time, or just want to relive the drama and magic of season one ahead of the season two premiere, viewers will get to see it on the platform where it all began…'bet on it!'”
Watch the season one marathon on May 8 beginning at 5 p.m. ET/PT on Disney Channel, which is also available to stream online with Live TV on Hulu and via FuboTV. Season two of High School Musical: The Musical: The Series premieres on May 14 on Disney+.