Parker was sold the following summer, moving to Newcastle United in July 2005 for a £6.5 million fee. He became a regular in the Newcastle first team and was one of the few players at the club to show any consistency during an often difficult season in which Newcastle finished in seventh place, despite having a very poor start under Graeme Souness. His first Newcastle goal came against his former club Charlton in a 3–1 defeat on 25 March 2006. Later that month he was diagnosed with glandular fever, putting an end to his season. The timing was especially unfortunate for Parker, who had been playing well for Newcastle, as it ended any hopes he may have had of forcing his way into the 2006 FIFA World Cup.