The Time of Our Lives received generally positive reactions from critics, with some reviews suggesting that the EP was an effective step into adulthood for Cyrus. Some reviews were critical of the ballads which appear on the record, however. The EP was a commercial success, charting within the top ten in nine countries. In the United States, The Time of Our Lives peaked at number two on the Billboard 200 and was certified platinum by the Recording Industry Association of America (RIAA). Moreover, the EP had success internationally, peaking at number three in Greece, number five in Austria, and number six in Spain.
Two singles were released from The Time of Our Lives. The lead single, "Party in the U.S.A.", became Cyrus' best-selling effort to date, peaking at number two in the Billboard Hot 100. It also became one of the best-selling singles in the United States and Hollywood Records' best- and fastest-selling single. The second and final single released from the EP was "When I Look at You". It was used to promote the 2010 film The Last Song, which Cyrus starred in. Unable to match "Party in the U.S.A."'s success, the single appeared in the top twenty of charts in Australia and the United States. Cyrus performed songs from The Time of Our Lives live numerous times. Her performance at the 2009 Teen Choice Awards caused a media uproar because of its sexuality. She embarked on her first world tour, the Wonder World Tour, to promote the EP in late 2009.