Some 70 soldiers from Burkina Faso are part of a planned deployment by regional bloc Ecowas.
A total of about 600 troops is expected over the coming days, according to an Ecowas statement. Guinea-Bissau was just weeks away from holding a presidential run-off vote when a military junta took over.
The Ecowas soldiers arrived on the same day as the prime minister of a transitional government, Rui Duarte Barros, was sworn into office. The coup leaders had earlier agreed to a 12-
month transition to civilian rule, as demanded by Ecowas.
The Ecowas peacekeepers are being deployed to "relieve the Angolan military personnel... and support the restoration of constitutional rule," its statement said.
About 200 Angolan officers have been in the country for the last year to help with training and reforms to the bloated army, which has long meddled in politics and is said by Western intelligence agencies to play a key part in trafficking drugs.
The soldiers who staged last month's revolt said the Angolan force was conspiring with Guinea-Bissau's government to "wipe out" the army.
No elected leader in nearly 40 years of independence has finished their time in office in Guinea-Bissau, which has now become a major staging post for gangs smuggling cocaine from Latin America to Europe.
The tiny West African nation is one of the world's poorest countries - with almost 70% of people living in poverty - and it is heavily dependent on foreign assistance.