Immune thrombocytopenia (ITP) is an autoimmune disease that occurs following viral illnesses and may also infrequently occur after measles, mumps, and rubella (MMR) vaccination. ITP typically presents with the sudden appearance of a petechial rash, bruising, and/or bleeding in an otherwise healthy-appearing child. However, ITP following MMR vaccine does not commonly cause severely depleted platelets. We report a case of ITP after MMR vaccination in a 13-month-old baby boy, who presented with petechial rash all over his body. The child had severe thrombocytopenia but was successfully treated with a single dose of intravenous immunoglobulin without complications. The study highlights that ITP post-MMR vaccine is an easily treatable condition.