This study will enroll participants with myelodysplastic syndromes (MDS) with an Isocitrate dehydrogenase protein, 1 (IDH1) mutation, who have not received treatment with a hypomethylating agent previously. Participants will be randomized to receive either ivosidenib (IVO) alone or azacitidine (AZA) alone. IVO will be administered daily throughout the 28-day treatment cycle and AZA will be administered for the first 7 days of each 28-day cycle. Study visits will be conducted every week during Cycle 1 (Days 1, 8, 15, and 22), and Day 1 of each cycle thereafter. After the last dose of treatment, participants will attend an safety follow-up visit and participants will be followed to assess overall survival. Study visits may include a bone marrow aspirate, physical exam, echocardiogram (ECHO), electrocardiogram (ECG), blood and urine analysis, and questionnaires.