Roberto Gualtieri arrived at Rome city hall this morning to take over officially from outgoing mayor Virginia Raggi, who leaves the office after five years.
Gualtieri, of the centre-left Partito Democratico (PD), was elected mayor after beating the centre-right candidate Enrico Michetti in a run-off vote on Monday.
"I wish Gualtieri all the best. Being a mayor is the most beautiful and complex job" - Raggi said in the Giulio Cesare hall - "On a human and political level it is a full experience. I have been honoured to lead this city, the most beautiful in the world, for five years."
Raggi, of the once anti-establishment Movimento 5 Stelle (M5S), joined Gualtieri on the balcony of his new office overlooking the Roman Forum, before the pair held talks described as cordial.
Gualtieri, 55, told reporters he would dedicate all his "commitment and passion" to the new role, adding: "I thank Raggi for the work of these years and now an intense and exciting phase for me begins."
In the meantime the new mayor is busy putting together his team to face a range of challenges ahead, from cleaning up the city's rubbish problem to developing the capital's bid for Expo 2030.
Raggi - who in addition to being the first woman to hold the office of Rome mayor was also the youngest at 37 - left the Campidoglio just after midday, to applause from her old staff, some of whom were in tears.
As Rome newspaper Il Messaggero put it: "On 23 June 2016 she arrived at city hall in an electric minicar, today she leaves in an Alfa Romeo."