The Socialist Party of Ukraine (Ukrainian: Соціалістична партія України, romanized: Sotsialistychna partiia Ukrainy, abbreviated SPU) was a social democratic and democratic socialist political party in Ukraine. It was one of the oldest parties in Ukraine and was created by former members of the Soviet-era Communist Party of Ukraine in late 1991, when the Communist Party was banned.

Involved in a number of popular protest movements in the early 2000s, it was third and fourth largest party in parliament during its time in parliament. The party entered government for the first time as part of a coalition with Our Ukraine and the Yulia Tymoshenko Bloc in 2005, but its decision to form a government with the opposing Party of Regions and the re-founded Communist Party of Ukraine in 2006 caused significant damage to the party's credibility. Despite historically strong support in the central regions of Ukraine, it failed to pass the 3% threshold to enter parliament in the 2007 parliamentary elections. From then onwards, the party's electoral results became increasingly marginal and it failed to win any seats in subsequent elections.

The party's founder, Oleksandr Moroz, was elected Chairman of the Verkhovna Rada, Ukraine's parliament, in 1994 and played a key role in the adoption of the Constitution of Ukraine. He led the party for more than 20 years until his resignation in 2012, after which the party became embroiled in a long-lasting leadership struggle. In 2017, the party was taken over by a former member of the far-right Right Sector, Illia Kyva. It participated in the 2019 presidential and parliamentary elections without any success.

The party was suspended in the wake of the Russian invasion of Ukraine and banned by a court decision on 15 June 2022.

Following Ukraine's independence on 24 August 1991, Leonid Kravchuk as the Chairman of the Verkhovna Rada (Ukraine's parliament) signed several important documents among which was the disbandment (26 August) and later the prohibition (30 August) of communist parties. This led to the collapse of the communist-majority faction, informally known as the "group of 239", led by Oleksandr Moroz. Four days after the prohibition of communist parties, Moroz called on communists to unite in a new left-wing party. The founding congress of the party was held in Kyiv on 26 October 1991 and Moroz was elected leader. The party's programme, approved at a second congress held in November 1992, emphasised the party's status as the successor to the Communist Party of Ukraine and proclaimed the party's goal of achieving socialism through "people's democracy".

In 1993, the party experienced a mass exodus of members when the Communist Party of Ukraine (KPU), which claimed to be the direct successor of the Soviet-era Communist Party, was formed in June. The situation was so severe that several of the party's regional organisations had ceased to exist and the continued existence of the party was put into question at an extraordinary congress, but those who supported merging into the Communist Party remained in the minority. In total, some 40,000 members, or half the party's membership, left for the refounded KPU.

In December 1993, the party entered the opposition to the administration of prime minister Leonid Kuchma and president Leonid Kravchuk, but by this point Kuchma had already resigned as prime minister.

In March 1994, the party participated in the country's first parliamentary election since independence and won 14 seats, becoming the fourth-largest party in the Verkhovna Rada behind the Communist Party, People's Movement of Ukraine (Rukh), and the Peasant Party of Ukraine (SelPU). By mid-1994, the party controlled a parliamentary faction of 25 deputies, as deputies from other parties, especially those from the Peasant Party of Ukraine (SelPU) opted to sit with the Socialists, and Moroz was elected Chairman of the Verkhovna Rada (speaker of parliament) with the support of Communist deputies.