Sjöstedt, who last week spent several days in Athens openly supporting Syriza's campaign, said on Monday that he was "very happy with the success of Syriza", adding that he hoped it would lead to "huge changes for people in Greece who had to suffer as a result of economic problems created by others."
He said that he could already see a 'Red Spring' emerging across Europe and said he hoped to see support for left-wing parties continuing to rise in Spain, Finland and Denmark, which are all holding elections later this year.
Syriza won Greece's general election on Sunday after its leader Alexis Tsipras vowed to end years of deep cuts in public spending and promised to stop what he called "five years of humiliation and pain".
With 36.4 percent of the vote, Syriza won't govern Greece alone, but will negotiate a coalition with a smaller right-wing party.
Jonas Sjöstedt's Left party scored just under six percent of the vote in Sweden's last general election in September.
Speaking to The Local on Monday, he said that he had been to visit an emergency health clinic and a food distribution centre in Athens last week where he had experienced "Greek poverty" first hand.
"Many of these kind of centres are basically run by left-wing groups because the power parties that have been governing Greece did not provide enough for the people there," he said.
The leader of Sweden's Left Party, Jonas Sjöstedt. Photo: TT
Green Party leader Simone Peter said that countries in crisis couldn't be fixed just by a "rigorous policy of cuts" and "tightening the noose".
Meanwhile Left leader Katja Kipping told German tabloid Bild that the election result was a "clear rejection of the cuts diktat, which is a social catastrophe and irresponsible for the national economy".
"We are now hoping for a red spring in Europe", she concluded.
But Syriza's victory has caused major concerns elsewhere on the political spectrum with many concerned it could trigger economic problems across Europe.
Greece has been supported with loans totalling around €240 billion from fellow EU member countries and the International Monetary Fund (IMF) and there are worries about what might happen if it seeks to reduce its debt repayments.
"The Greeks have to bear the consequences of their own actions and can't saddle the German taxpayer with them", Christian Democratic Union (CDU) deputy leader in the Bundestag (German parliament) Hans-Peter Friedrich told German tabloid Bild's Monday edition.
Sweden's Social Democrat Finance Minister Magdalena Andersson told Swedish broadcaster SVT that she was concerned about what might happen if Greece ended up adopting its own currency again and exiting the Eurozone.
"The loans were made in euros, and if the Greeks aren't using that currency, it'll be hard for them to pay it back," she said.
Britain's Prime Minister tweeted: "The Greek election will increase economic uncertainty across Europe. That's why the UK must stick to our plan, delivering security at home."
Reacting to the criticism, Sjöstedt said that any current economic problems were caused "not by the Greek people but by the bankers who triggered the crisis".
"Right-wing economics did not work and Syriza was the only way out to bring change in Greece."
But he conceded that Syriza was "not in any way perfect" and as a relatively new political party, would no doubt face "tremendous difficulties" as it sought to shift the country in a new direction.
"Things are definitely already changing in Spain with the success of the left wing party Podemos. I think Spain could be the next one to follow and the Spanish economy is even more important to the EU than Greece."