Sombr turned his Thursday night Lollapalooza set into a reunion moment when he brought out 5 Seconds of Summer as surprise guests on the T-Mobile mainstage in Chicago. The two acts performed 'She Looks So Perfect' together — the 2014 single that put the Australian band on the map globally — to a crowd that, by all accounts, did not see it coming. (Rolling Stone)

Neither act was a stranger to the festival grounds. Both Sombr and 5 Seconds of Summer were listed in the official Lollapalooza 2026 lineup when it was announced in March, alongside headliners Charli xcx, Olivia Dean and Tate McRae, with Lorde also on the bill. (Billboard; Variety)

Sombr's set was theatrical from the start. He arrived on stage in a car driven from backstage, drink in hand, dressed in an all-black outfit that included a lace T-shirt, a feather-adorned coat and a boa. The stage design leaned into a New York aesthetic, with street signs and a construction sawhorse scattered across the platform. At one point, he ran into the audience carrying a black flag spray-painted with his name and the word 'Lollapalooza'.

Before the surprise guest appearance, he had already run through several of his own songs: 'My Body Isn't Ready', 'Potential' and 'Homewrecker'. The last of those was named to Rolling Stone's best songs of 2026 list. 'Homewrecker' appears on Sombr's debut album 'I Barely Knew Her', released in August 2025.

The Lollapalooza appearance follows a busy year for the artist. He performed at the 2026 Grammy Awards and played Coachella earlier in 2026, where Billy Corgan joined him on stage. Corgan's own band was scheduled to headline Lollapalooza the Friday night after Sombr's Thursday set — a booking thread that connects the two appearances across the festival circuit.

Looking ahead, Sombr is scheduled to embark on a North American arena tour in autumn 2026, ending with a date at Madison Square Garden in New York on 23 November.

For fans of 5 Seconds of Summer, the Lollapalooza cameo was a rare sighting. The band has kept a relatively low public profile in recent months, and the surprise duet placed them back on one of the summer's largest stages — if only for one song.