Though not all votes have been counted, opponents of the 37-year-old populist and social media star acknowledged his victory, according to TSE.
TSE said most of the votes, almost 90%, have been counted and Bukele won 54% of the vote.
The future of the gang and poverty-ridden country may have an impact on the flow of migrants
-- many of whom come from El Salvador -- to the US-Mexico border.
Leaders of other Central American countries took to social media to congratulate Bukele.
Panama's president, Juan Carlos Varela, wrote he will "work hand in hand with this sister nation," and praised Bukele's win after a "democratic and peaceful electoral feast."
Carlos Alvarado Quesada, the president of Costa Rica, also sent his congratulations vowing to deepen the country's friendship with El Salvador as well as a "common agenda of values and purposes for our region."
Venezuela's self-declared interim president, Juan Guaido also chimed in, calling the election day "exemplary."
"Our country is ready to realize soon a new stage of relations, based on collaboration and observation of the highest democratic values," he wrote on Twitter.