Deadly protests have hit the nation since last month as President Pierre Nkurunziza seeks to extend his 10-year rule.
The President has a two-term limit as part of an agreement that helped end Burundi's ethnic civil war. Critics say his planned run violates the constitution.
The election commission confirmed Friday that Nkurunziza has officially registered to run in next month's election.
Burundi's constitutional court ruled this week that he is eligible because he was picked by parliament, not elected by people, during his first term.
At least seven candidates have registered for the presidential race. Among them is prominent opposition leader Agathon Rwasa, who helped lead rebel fighters in the country's 1993-2003 civil war.
As clashes between police and protesters have raged, the international community has urged both sides to refrain from violence.
They have not complied, with the clashes sending an alarming flow of refugees to neighboring nations.
Already, 50,000 refugees have streamed into the Democratic Republic of Congo, Tanzania and Rwanda, half of them in the latter nation, according to the United Nations.
History of tensions
The current tension seems on its face to revolve around politics rather than ethnicity.
It boils down to the determination of Nkurunziza to hold onto power and protesters whose goal is to prevent his candidacy. But Burundi's history of ethnic violence makes it especially vulnerable to deep divisions.
Tensions between ethnic Hutus and Tutsis fueled the country's civil war. It left an estimated 300,000 people dead.
The situation can escalate quickly, said Nsengiyumva Pierre Claver, a former member of a European Union electoral monitoring team.
"The rules in this deadly game now can change so easily," said Claver, who is in the capital of Bujumbura. "There is a very great risk of ethnic conflict."
Violence between Hutus and Tutsi in Burundi could spill into neighboring Rwanda and in the eastern part of the Democratic Republic of Congo.
In the latter two nations, Hutus and Tutsis endure an uneasy coexistence, sparking fears that broader violence could erupt.