<b>Background:</b> Low-dose glucocorticoid (GC) therapy is widely used in rheumatoid arthritis (RA) but the balance of benefit and harm is still unclear. <b>Subjects and methods:</b> The GLORIA (Glucocorticoid LOw-dose in RheumatoId Arthritis) pragmatic double-blind randomised trial compared 2 years of prednisolone, 5 mg/day, to placebo in patients aged 65+ with active RA. We allowed all cotreatments except long-term open label GC and minimised exclusion criteria, tailored to seniors. Benefit outcomes included disease activity (disease activity score; DAS28, coprimary) and joint damage (Sharp/van der Heijde, secondary). The other coprimary outcome was harm, expressed as the proportion of patients with ≥1 adverse event (AE) of special interest. Such events comprised serious events, GC-specific events and those causing study discontinuation. Longitudinal models analysed the data, with one-sided testing and 95% confidence limits (95% CL). <b>Results:</b> We randomised 451 patients with established RA and mean 2.1 comorbidities, age 72, disease duration 11 years and DAS28 4.5. 79% were on disease-modifying treatment, including 14% on biologics. 63% prednisolone versus 61% placebo patients completed the trial. Discontinuations were for AE (both, 14%), active disease (3 vs 4%) and for other (including covid pandemic-related disease) reasons (19 vs 21%); mean time in study was 19 months. Disease activity was 0.37 points lower on prednisolone (95% CL 0.23, p < 0.0001); joint damage progression was 1.7 points lower (95% CL 0.7, p = 0.003). 60% versus 49% of patients experienced the harm outcome, adjusted relative risk 1.24 (95% CL 1.04, p = 0.02), with the largest contrast in (mostly non-severe) infections. Other GC-specific events were rare. <b>Conclusion:</b> Add-on low-dose prednisolone has beneficial long-term effects in senior patients with established RA, with a trade-off of 24% increase in patients with mostly non-severe AE; this suggests a favourable balance of benefit and harm. <b>Trial registration number:</b> NCT02585258.