has a female president for the first time, after ex-president Pedro Castillo
was impeached - hours after he tried to dissolve parliament.
Dina Boluarte - previously the vice-president - was sworn in after a dramatic day in Lima.
Earlier in the day, Mr Castillo had said he was replacing Congress with an "exceptional emergency government".
But lawmakers ignored the announcement, and in an emergency meeting impeached the president.
Ms Boluarte, a 60-year-old lawyer, said she would govern until July 2026, which is when Mr Castillo's presidency would have ended.
Speaking after taking the oath of office, she called for a political truce to overcome the crisis which has gripped the country.
"What I ask for is a space, a time to rescue the country," she said.
Wednesday's dramatic chain of events began with President Pedro Castillo giving an address on national television in which he declared a state of emergency.
Pedro Castillo: The primary school teacher who became Peru's president
He announced that he would dissolve the opposition-controlled Congress, a move which was met with shock both in Peru - several ministers resigned in protest - and abroad.
The head of the constitutional court accused him of launching a coup d'etat, while the US "strongly urged" Mr Castillo to reverse his decision.
Peru's police and armed forces released a joint statement in which they said they respected the constitutional order.
Mr Castillo tried to dissolve Congress just hours before it was due to start fresh impeachment proceedings against him - the third since he came to office in July 2021.
In his televised address he said: "In response to citizens' demands throughout the length and breadth of the country, we have decided to establish an exceptional government aimed at re-establishing the rule of law and democracy."
He said that "a new Congress with constituent powers to draw up a new constitution" would be convened "within no more than nine months".
But Congress, which is controlled by parties opposed to Mr Castillo, convened an emergency session and held the impeachment vote Mr Castillo had been trying to prevent.
The result was overwhelming: 101 voted in favour of impeaching him, with only six against and 10 abstentions.
After the impeachment, Castillo was seen on police premises - it is unknown if he was arrested, or whether he decided to attend.
In the photos - which were shared by police on Twitter but subsequently deleted - he could be seen sitting, seemingly relaxed, and chatting to others.
Footage was then released of Mr Castillo signing papers with prosecutors.
Peru has been going through a rocky political period, with multiple presidents ousted from office in recent years. In 2020, it had three presidents within the space of five days.
Mr Castillo, who is a left-wing former school teacher, was elected in June 2021 in a polarising election in which he defeated his right-wing rival Keiko Fujimori.
He had recently been fighting allegations of corruption, which he said were part of a plot to oust him.