Shortly after Lula was declared the winner, US President Joe Biden said: "I send my congratulations to Luiz Inacio Lula da Silva on his election to be the next president of Brazil following free, fair, and credible elections."
Germany also welcomed Luiz Inacio Lula da Silva's victory in Brazil's presidential election, calling it a win for democracy and climate protection.
"The biggest winner is Brazilian democracy because the elections, which were very close, were transparent and fair," Foreign Minister Annalena Baerbock told reporters during a visit to Astana.
Likewise, Spanish Prime Minister Pedro Sanchez hailed Luiz Inacio Lula da Silva's victory in Brazil's presidential election, urging the two nations to work together to fight climate change.
"Congratulations Lula on your victory... Let's work together for social justice, equality and against climate change," Sanchez tweeted. "Your success will be the success of the Brazilian people."
French leader Emmanuel Macron also offered his good wishes, saying the poll opened "a new page" in Brazil's history.
"Together, we will join forces to take up the many common challenges and renew the ties of friendship between our two countries," the French president said minutes after the results announcement.
While Canadian Prime Minister Justin Trudeau offered a hearty "Congratulations, Lula!" and said: "The people of Brazil have spoken."
Trudeau said he looked forward to working with Lula, who served as Brazil's president from 2003 to 2010, to "advance shared priorities -- like protecting the environment."
Similarily, Norway in a gesture of goodwill announced it would resume sending Amazon protection subsidies to Brazil, which it had halted in 2019 under Jair Bolsonaro, following Luiz Inacio Lula da Silva's election victory.
"We had a good and very close collaboration with the government before Bolsonaro and deforestation in Brazil declined greatly under Lula da Silva's (previous) presidency", Environment Minister Espen Barth Eide told AFP.
Whereas Britain's newly elected Prime Minister Rishi Sunak said he looked forward to working together on issues, including "growing the global economy to protecting the planet's natural resources and promoting democratic values."
President Alberto Fernandez of neighboring Argentina said Lula's win "opens a new era for the history of Latin America. A time of hope and future that begins today."
"After so many injustices you lived through, the people of Brazil have elected you and democracy has triumphed," he added in a tweet.
After leaving office, Lula was imprisoned for 18 months on controversial and since-quashed corruption charges.
Lula's return to power in Brazil follows a string of left-wing wins in Latin America.
Gustavo Petro, who became Colombia's first leftist president after his election this summer, tweeted "Long live Lula."
He later shared a map showing that the majority of Latin American countries are now led by leftist governments.
Mexico's President Andres Manuel Lopez Obrador, also from the left wing, tweeted: "Lula won, blessed people of Brazil. There will be equality and humanism."
And Venezuelan President Nicolas Maduro offered a "big hug" to Lula, saying in a tweet: "Long live the peoples determined to be free, sovereign and independent! Today in Brazil democracy triumphed."
Fellow members of the BRICS group of emerging economies also extended their congratulations.
Russian President Vladimir Putin said he hoped for "constructive" cooperation.
"Please accept my sincere congratulations... the election results have confirmed your impressive political authority," Putin said in a telegram to Lula.
Chinese leader Xi Jinping wished the country "new successes."
"I am willing to work with President-elect Lula to make joint plans from a strategic height and long-term perspective, and take the China-Brazil comprehensive strategic partnership to a new level," he said.
Indian Prime Minister Narendra Modi said he looked forward "to working closely together to further deepen and widen our bilateral relations."
South African President Cyril Ramaphosa also said his country "looks forward to working with the government of Brazil under the leadership of Mr da Silva."
The European Union's chief diplomat Josep Borrell joined the international chorus.
"Brazilian citizens went to the polls to elect their new president in a peaceful and well-organised election."
Head of the European Commission Ursula von der Leyen also expressed her optimism, saying she is looking forward to working with Lula.
"I look forward to working with you to address pressing global challenges, from food security to trade and climate change," von der Leyen told Lula, in a congratulatory tweet.