NEW IDEAS PARTY DEPUTY WILLIAM SORIANO: "Bitcoiners around the world, the time has come. We are ready."
The Congress approved the bill by a supermajority, despite concerns the move could complicate talks with the International Monetary Fund, from which El Salvador is seeking more than $1 billion in financial support.
One of the few lawmakers who voted against the bill expressed his misgivings.
ARENA PARTY DEPUTY JOHN WRIGHT: "For some, this is bold. For others, irresponsible. But it's a bet, as well as an experiment. I regret how this has come to pass, and what's behind it. And I hope, for the good of the country, to be proven wrong."
In a tweet, President Nayib Bukele cheered the approval in Congress, which is controlled by his party and allies, one of whom echoed his exuberance for embracing the virtual currency.
GRAND ALLIANCE FOR NATIONAL UNITY DEPUTY, GUILLERMO GALLEGOS: "This is an important step for our country. A step for technology, a step into the future to bring us financial inclusion, investment, tourism, innovation, economic development to our country."
Regulators and policymakers all over the world have warned about Bitcoin's volatility, and that it facilitates money laundering and other illicit uses.
Bukele, who proposed the law to make Bitcoin legal tender, has touted the use of cryptocurrency for its potential to help Salvadorans living abroad to send money back home.
Bukele has even more ambitious plans for Bitcoin, saying later on Wednesday that he wanted to use renewable energy from the country's volcanoes to offer Bitcoin mining facilities - which generate new units of the cryptocurrency - and instructed the state-owned geothermal energy firm to come up with a plan to make it happen.
Meanwhile, Bitcoin enjoyed its best day in two weeks following the vote in El Salvador, rising as much as 6% to more than $35,000.