Objective <p>To describe the imaging features of osteonecrosis of the femoral head (ONFH) on ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/CT and explore whether PET/CT can raise suspicion for ONFH in patients with lymphoma.</p> Methods <p>A retrospective analysis was conducted on the clinical data, PET/CT, and MRI findings of 17 patients with lymphoma and ONFH. The ¹⁸F-FDG uptake of ONFH was recorded, and the maximum standardized uptake value (SUV_max) of ONFH was measured. The staging and extent of ONFH, and other bone involvements, were visually assessed. Lymphoma disease status was evaluated using the Deauville criteria.</p> Results <p>A total of 31 femoral heads were involved (2 stage 1, 24 stage 2, 4 stage 3, 1 stage 4). The median SUV_max was higher in stage 3–4 lesions (5.27) than in stage 1–2 lesions (1.37) (<i>P</i> = 0.002). Regarding ¹⁸F-FDG uptake patterns, all stage 1 lesions showed normal uptake; among stage 2 lesions, 11 showed increased uptake, 5 showed peripheral increased with central decreased uptake, 2 showed decreased uptake, and 6 showed normal uptake; all stage 3–4 lesions demonstrated increased uptake. On CT, the extent of all stage 2–4 lesions matched MRI findings. Nine patients had osteonecrosis in other bones, including the humeral heads (<i>n</i> = 9), bilateral iliac bones (<i>n</i> = 6), and vertebrae/ribs/scapulae (<i>n</i> = 1).</p> Conclusions <p>In patients with lymphoma, ONFH exhibits variable degrees of ¹⁸F-FDG uptake and may be accompanied by involvement of other bones. PET/CT may raise suspicion for ONFH and detect multiple bone involvements during lymphoma assessment.</p>