The Mansion was built in 1908 to serve as the official summer residence of U.S. Governor-Generals at the instance of Governor-General William Cameron Forbes. The name is derived from the summer cottage in New England of Governor Forbes whose administration the original Mansion House was built under. Architect William E. Parsons, based on preliminary plans by architect Daniel H. Burnham, the planner of the city of Baguio, designed the mountain retreat following the tenets of the City Beautiful Movement. In 1910, the meeting of the Second Philippine Legislature was held at The Mansion for three weeks.The house was badly damaged during the Second World War and was rebuilt in 1947. Since then, it has served as the holiday home and working office for each President of the Philippines during his or her visits to Baguio.

The Mansion House was also used as the venue of important events, such as the second session of the United Nations Economic Commission for Asia and the Far East (ECAFE) in 1947, the second session of the Food and Agriculture Organization in 1948, and the first meeting of the Southeast Asian Union (SEAU), more commonly known as the Baguio Conference of 1950, which was conceived and convened by President Elpidio Quirino. More recently, The Mansion has been the site of a number of international conferences.