Despite exit polls predicting the triumph of a liberal centrist party, the Smer-SSD party held a commanding lead with nearly 24% of the vote.
Smer has promised to put an immediate stop to Ukraine's military backing.
Following the assassination of investigative journalist Jan Kuciak in 2018, Mr. Fico was obliged to resign as prime minister.
He is anticipated to begin coalition negotiations to create the next government.
With nearly all votes counted, a populist pro-Moscow party led by former prime minister Robert Fico has won Slovakia's parliamentary elections.
Despite exit polls predicting the triumph of a liberal centrist party, the Smer-SSD party held a commanding lead with nearly 24% of the vote.
Smer has promised to put an immediate stop to Ukraine's military backing.
Following the assassination of investigative journalist Jan Kuciak in 2018, Mr. Fico was obliged to resign as prime minister.
He is anticipated to begin coalition negotiations to create the next government.
According to exit surveys, the liberal Progressive Slovakia party received roughly 17% of the vote.
With 15% of the vote, the pro-European Hlas party came in third and might determine who forms the next government.
Peter Pellegrini, the left-leaning leader of Hlas and a former Fico partner, kept his options open for potential coalitions.
"The distribution of seats confirms Hlas as a party without which any normally functioning government coalition cannot be put together," Mr. Pellegrini said.
Mr. Fico may support the nationalist Slovak National Party, which garnered 5% of the vote, and Hlas, which broke away from Smer in 2020.
With up to 10 parties, ranging from libertarians to the far-right, in the new parliament, the coalition-building process may be drawn out and difficult.
Mr. Fico recently promised supporters that "we will not send a single round of ammunition to Ukraine" if Smer takes office.
Members of the European Union and NATO have expressed worry over the threat, while Slovaks who have historically had positive views of Moscow have expressed support for it on social media.
In addition to providing surface-to-air missiles, helicopters, and even its complete fleet of decommissioned MiG-29 fighter jets, Slovakia has been a devoted and faithful ally of Kiev.
Smer rejects such ideology as "liberal fascism" and runs his campaign on social security, stability, and law and order. Mr. Fico has also expressed alarm about the increase in the number of migrants passing through Slovakia on their way to western Europe.
BBC