Poroshenko's swearing-in as president at a pomp-filled, but relaxed, ceremony on Saturday conveyed the feeling that a line had been drawn under the six months of upheaval which toppled his predecessor, Viktor Yanukovich.
The 48-year-old businessman is expected in the coming days to name new foreign and defence ministers. Valery Chaly, a key ally, who was in charge of foreign policy issues during Poroshenko's campaign, looks a shoo-in for the foreign minister's job.
Another key ally will be Prime Minister Arseny Yatseniuk, himself a former economy minister, who has already pledged to work "as a single whole" with the president and parliament.
An early test for the new leader will be yesterday's trilateral talks in Brussels aimed at solving a dispute over the price of Russian gas.
Russia had threatened to cut off supplies to its neighbour, a major gas transit route to the European Union, if it fails to pay its debts to Gazprom by today.
Poroshenko's blunt refusal to accept the loss of Crimea in a combative inaugural speech has already put him at odds with his Russian counterpart, Putin.