On January 14, 2020, Baker announced the title of the project as Tickets to My Downfall, and that it would be released on September 25, 2020.[48] On March 17, 2020, he released the song "Bullets with Names", featuring Young Thug, RJMrLA and Lil Duke, a rap track not associated with the album.[49] Releases included covers of "Misery Business" by Paramore (with Travis Barker), "Champagne Supernova" by Oasis (with Yungblud), and a remix of "My House" by PVRIS. Some tracks were later re-released on special editions of Tickets to My Downfall. Tickets to My Downfall's first single "Bloody Valentine" was released on May 1, 2020, followed by "Concert for Aliens" on August 5 and "My Ex's Best Friend" featuring Blackbear on August 7.
In August 2020, Baker opened his own coffee house called 27 Club Coffee in his hometown of Cleveland, Ohio. On September 29, 2020, a music video was released for the Tickets to my Downfall song "Drunk Face", directed by Mod Sun, which was followed on October 22, 2020, by a music video for "Forget Me Too". Throughout October 2020, the four episodes of Halloween in Hell, a fictionalised musical horror podcast that Baker created and starred in, were released. The series also starred Iann Dior, 24kGoldn, Dana Dentata, Phem and Tommy Lee. The podcast was accompanied by the album Audio Up presents: Original Music from Halloween In Hell a soundtrack performed collaboratively by all the actors involved, and written and composed by Jared Gutstadt. Baker directed the music video for Mod Sun's song "Karma", which was released on November 12, 2020.
On November 22, 2020, after his performance at the AMAs, Baker announced his album Tickets to My Downfall was going to be turned into a "first if it’s kind musical film experience" titled Downfalls High which will air in January 2021. On November 30, 2020, Yungblud announced on Twitter he'll be releasing a new collaboration featuring Baker and Travis Barker titled "Acting Like That". On January 15, 2021, Baker released Downfalls High on his Facebook page followed by a release to YouTube on January 18. Directed by Baker and Mod Sun and narrated by Baker and Barker, the film stars Chase Hudson and Sydney Sweeney as teenage lovers in what Baker described as a "pop-punk [version of] Grease". Iann Dior, Phem, Jxdn, and Trippie Redd, also make appearances.
On March 12, 2021, he released the single "DayWalker" featuring Corpse Husband. On April 29, he released the single "Love Race" featuring Kellin Quinn, the pair's third collaboration.
On August 9, 2021, he announced that his next album would be titled Born with Horns, and would be another collaborative project with Barker. The first single, "Papercuts", was released on August 11. On January 30, 2022, he posted a preview of a collaboration with singer Willow titled "Emo Girl".
On August 26, 2021, it was announced that he would star in and co-direct the film Good Mourning with a U, alongside Mod Sun, Dove Cameron, Megan Fox and Becky G. On February 5, 2022, Machine Gun Kelly performed during the 2022 NHL All-Star Game halftime show in Las Vegas.
On January 31, 2022, Kelly announced that the album had been retitled to Mainstream Sellout.