Unitary Socialist Party may refer to:

• Unitary Socialist Party (Romania) (1933-1938), a political party in Romania
• Unitary Socialist Party (Italy, 1922) (1922–1930), a political party in Italy
• Unitary Socialist Party (Italy, 1949) (1949–1951), a political party in Italy
• A denomination of the Italian Democratic Socialist Party (1969–1971)