A Bosman transfer to Portsmouth followed after three successful seasons at the Berkshire-based club. Initially, Primus struggled to break into the team and had his progress hindered by injuries. But the 2002–03 season signaled a change in direction as Primus broke into the first team and won Portsmouth fan's player of the season as well as the PFA Fans' Player of the Year for his division. For the next three seasons Primus was in and out of the first team and worked under three managers: Harry Redknapp, Velimir Zajec and Alain Perrin. The 2006–07 season was the last injury-free season for Primus as a career-threatening knee injury meant he would not make an appearance the following season. Primus went out on loan to former club Charlton and made 10 appearances and one further appearance for Portsmouth before retiring through injury in December 2009. The Milton End stand at Fratton Park was renamed the 'Linvoy Primus Community Stand' because of his outstanding services to the club.