The incidence of invasive group B streptococcus (GBS) infections in non-pregnant adults is increasing. Little is known about GBS in periprosthetic joint infections (PJIs). We aimed to analyse the clinical presentation of GBS PJI and its treatment in association with the outcome. The characteristics of 36 GBS PJIs collected from 10 centres were investigated. In 34 episodes, follow-up examination of ≥ 2 years was available, allowing treatment and outcome analysis. Most infections (75%) occurred ≥ 3 months after implantation. Most patients (91%) had at least one comorbidity; 69% presented with acute symptoms and 83% with damaged periprosthetic soft tissue. In 20 of 34 episodes debridement and retention of implant was attempted, but in five of these the prosthesis was ultimately removed. Hence, in 19 (56%) episodes, the implant was removed, including 14 immediate removals. In four episodes the removal was permanent. Penicillin derivatives and clindamycin were the most common antimicrobials administered (68%). In 94% the infection was cured, and in 82% functional mobility preserved. Debridement with implant retention was successful if the duration of symptoms was short, the prosthesis stable, and the tissue damage minor (10/10 vs 3/10 episodes, P = 0.003). Surgery that complied with a published algorithm was associated with a favourable outcome (P = 0.049).