However, there is no honeymoon for the new leader as he flies to Peru tomorrow to attend an Apec summit focusing on the international financial and economic crisis.
Mr Key touched on the challenges faced by New Zealand at the ceremony where he and his ministers were sworn into their roles by Governor General Anand Satyanand at Parliament.
His first duty was to chair Cabinet this afternoon before flying to Peru tomorrow to attend Apec. Two of his 20-strong Cabinet, Murray McCully and Tim Groser, were not at the ceremony as they have already left for Peru.
Speaking to reporters, Mr Key said being sworn in was a wonderful feeling.
"Obviously there's the enormity of the task that stands in front of us but, as I said, I've never felt more confident that the group of individuals that form the executive are the right individuals to take New Zealand on a more prosperous and safer future," he said.
Mr Key forged support agreements with three minor parties to give him 70 confidence votes in the 122-member Parliament. There are three ministers outside of Cabinet plus the five support party MPs who hold ministerial roles; Maori Party co-leaders Tariana Turia and Pita Sharples, ACT's Rodney Hide and Heather Roy and United Future leader Peter Dunne.
The ceremony was formal, only broken by Maori MPs Hone Harawira and Te Ururoa Flavell performing a haka to greet their leaders as they took their places. They also made the occasional remark from the sidelines, saying kia ora to Paula Bennett and Georgina te Heuheu and calling their party leaders "minister".
In brief remarks at the end of the swearing-in, Mr Key thanked the public for voting for all the parties represented there.
He told journalists that looking down the long polished table in Parliament's grand hall he felt proud of the achievement.
"I felt very proud actually that we'd managed to put together an executive that was well balanced, that represented greater diversity, and is an executive that I am very proud of."
Tonight would be spent preparing for his trip but there would be some celebration. "I am sure there will be a glass of something nice when I get home."
Mr Key's boyhood dream to lead the country was now fulfilled.
"In recent times it has felt as though it may occur but, obviously with the electoral system and MMP and all of those challenges, you never really know."
Unprompted, Mr Key offered advice for the next generation of aspiring leaders.
"I think if I had a message for young New Zealanders who want to be in my shoes in a few years to come it would be that they should live their dream and just to recognise that you get out of life what you put into it and maybe they can fulfil whatever their dream might be."
Mr Key said it was now time to get to work.
"I think the last nine days we've just put our nose to the grindstone and New Zealanders can take some confidence that we put together a government quickly but professionally and with a strong cabinet and that demonstration of leadership over the last nine days I intend to ensure is continued over the next three years."
