Released as a single in 1977, it reached the Top Ten in the
UK Singles Chart. Reviewing the single,
Evening Herald said that it "storms along in great style."
Santa Barbara News-Press critic Bill Milton complained that the rock and classical elements don't always jell.
Houston Post critic Bob Claypool called it "overinflated", describing it as being "basically a steal from Little Richard's '
I'm Ready' with quasi-operatic effects thrown in." ELO biographer Barry Delve called "Rockaria!" "one of ELO's best hard rockers; successfully blending opera, a full orchestra and choir" as well as "a cheeky backwards nod to
Beethoven's fifth symphony" played on the piano by
Richard Tandy. Guarasco felt that it "could very well be the most impressive of the group’s recordings" and that "the novelty of the sound and the imagination poured into "Rockaria" should have made the song a hit in America." He also said that the song is "rightly considered to be one of Jeff Lynne’s finest achievements on record." ==B-side==