Abstract Background Long COVID is prevalent and costly. There is much debate around the effectiveness and tolerance of exercise among people with Long COVID due to the potential to exacerbate symptoms. Therefore, this systematic review aimed to examine the effectiveness and tolerance of exercise interventions among people with Long COVID as part of a wider project to inform updates to the Irish Health Service Executive’s Long COVID interim model of care. Methods Medline via EBSCOhost, Embase, and CENTRAL were systematically searched on 28 February 2023. Inclusion criteria were: (1) participants with Long COVID; (2) random assignment to either an exercise intervention or a comparison group; (3) a quantitative measure of at least one of 12 core Long COVID outcomes. Two reviewers independently extracted data and assessed study risk of bias using the Cochrane Risk of Bias tool. Results In total, 4,394 studies were identified, 569 full texts were screened, and eight studies were included. Follow up periods ranged from two to 28 weeks (mean=8.5 weeks). Sample sizes ranged from 39 to 119 (mean=56). All studies were in adults (mean age=49.9 years) and both sexes (mean female proportion=53.9%). Four studies were at low risk of bias, two unclear, and two high. The evidence suggests that exercise interventions led to short-term improvements in dyspnoea, fatigue, physical function and the physical domain of quality of life. Of the five studies that reported adverse events, rates were low and, when reported, mild. Of the seven studies that reported sufficient information, one of 252 participants who received exercise discontinued the intervention due to tolerance-related issues. Conclusions Available evidence suggests that exercise interventions may have short-term benefits and be tolerable among some people with Long COVID. However, the evidence base consists of a limited number of studies with small sample sizes and short follow-up periods. Key messages • There is much debate around the effectiveness and safety of exercise among people with Long COVID due to the potential to exacerbate symptoms. • The available evidence suggests that appropriate exercise interventions may have short-term benefits and be tolerable. However, there are notable limitations among the evidence.