Rosenberg began his career at hometown club Malmö FF and became the Allsvenskan top scorer while on loan at Halmstads BK during the 2004 season. Rosenberg's Allsvenskan success attracted interest from abroad, and ultimately he ended up playing for football clubs all across Europe, including Werder Bremen in the German Bundesliga, Ajax in the Eredivisie, Racing de Santander in La Liga, and West Bromwich in the English Premier League. After returning to Malmö FF in 2014, Rosenberg scored several key goals in the club's UEFA Champions League run and helped the team win the league title. The following year, Rosenberg once again played a pivotal role in securing consecutive group stage qualifications for Malmö FF in the Champions League. He was also involved in winning two more consecutive league titles in 2016 and 2017, as well as advancing past the 2018–19 and 2019–20 UEFA Europa League group stage levels with Malmö. His second spell at Malmö FF proved to be successful, as he was named the club's greatest footballer in the 21st century.