Lights hit the big disco ball above LCD Soundsystem during the first song of its set on Sunday night, headlining the Panorama Festival on Randalls Island. “The time has come today,” band members sang in “Us v Them,” and the disco ball blasted a simple, unmistakable message: Time to dance.

LCD Soundsystem was making a return and a homecoming. In 2011, the group announced it was disbanding, and it played (and filmed) a farewell show at Madison Square Garden — the big arena in the band’s hometown, a gesture as final as LCD’s leader, James Murphy, could make it.

But it wasn’t final after all. This year, Mr. Murphy announced that he had written a lot of new songs and the band had regrouped (and bought back some of its old equipment) to play them. LCD Soundsystem has been playing festival dates since Coachella in April, but the band has always identified itself — in lyrics, sound and sensibility — with New York City, and the inaugural Panorama Festival was canny enough to make the band the finale of its three-day lineup, following a performance by the pop singer and songwriter Sia. “It’s very nice to play at home,” Mr. Murphy said.