The Portman Chapel was constructed in 1779 as a chapel serving the Portman Estate, newly laid out in this area. The chapel fell within the parish of Saint Marylebone. In December 1831 the church became the parish church of Saint Paul. In 1870 the church was rebuilt and expanded. In 1901 it was reconsecrated as the parish church of Saint Paul, Portman Square. After the Second World War the population of the area decreased and the parish was united to All Souls' Langham Place (P89/ALS). The church was closed and demolished in 1972. It was replaced by Saint Paul's, Robert Adam Street, which was consecrated in 1970.
The chapel should not be confused with the Portland Chapel, Great Portland Street, which was also renamed Saint Paul's (P89/PAU1).