A popular choice for lateral epicondylitis (LE), corticosteroid injections have been associated with prominent side effects, which has led to the conception of modalities like platelet-rich plasma (PRP). This randomised trial aimed to evaluate and compare the 6-week, 3-month and 1-year outcomes with PRP and corticosteroid injections in LE. We hypothesised that PRP would prove more effective in relieving pain and improving function. At the sports medicine unit of our tertiary care teaching centre, 80 patients with LE were randomised into either receiving PRP (group A) or corticosteroids (group B) injections. Pre-injection visual analogue scale (VAS), disabilities of the arm, shoulder and hand (DASH) score, Mayo elbow performance score (MEPS) and grip strength score (GSS) were recorded. Common extensor origins were identified and infiltrated with 3 ml of either PRP or corticosteroid (triamcinolone in 2% xylocaine) using a peppering technique. Follow-up scores and extent of pain relief were recorded and compared. At 6 weeks, there were greater improvements in group B versus A in mean VAS (13.8 vs. 44.5; p < 0.001), DASH (64.2 vs. 53.3; p < 0.001), MEPS (88.0 vs. 74.5; p = 0.004) and GSS (89.3 vs. 73.4; p = 0.039). These scores showed a reversed pattern at 3 months when group A outcomes superseded group B (VAS p = 0.002; DASH p < 0.001; MEPS p = 0.002; GSS p = 0.045). At 1-year follow-up, group A continued to enjoy better pain relief and function (VAS p = 0.024; DASH p < 0.001; MEPS p = 0.009; GSS p = 0.028). Albeit corticosteroid injections show good short-term results at 6 weeks, patients receiving PRP injections fare better at 3 and 12 months.