This is a multicenter, open-label Phase 1/2 study of vimseltinib in patients with malignant solid tumors and tenosynovial giant cell tumor (TGCT). There will be 2 distinct parts in this study: Dose Escalation (Phase 1) and Expansion (Phase 2). Phase 1 will enroll both malignant solid tumor and TGCT patients. Phase 2 will comprise two cohorts (Cohort A and Cohort B) and will only enroll TGCT patients.