Former Prime Minister Stephen Harper has officially resigned his seat in the federal riding of Calgary Heritage on Friday, announcing his decision on social media.

"For a total of nearly 18 years, I have had the tremendous honour of representing Calgary in the Parliament of Canada. On seven occasions, I have been deeply humbled by your trust and support, time and again," Harper said in a statement released on Friday.

After months of rumours, Harper has decided to leave politics and launch an international business development firm.

The new company, that will also involve two of his most trusted former advisors, will be based in Calgary and will be named Harper and Associates.

"As I bid farewell to the Parliament of Canada and prepare for the next chapter in my life, my eternal thanks to the constituents of Calgary Heritage, to the members of the Conservative Party and to all Canadians for having given me the honour of serving the best country in the world."

Rona Ambrose, the interim leader of the Conservative Party of Canada, thanked Harper's leadership in a statement released on Friday morning.

"I took the opportunity to thank him for everything he has done - for the people of Calgary Heritage and Calgary Southwest before that, for proud conservatives everywhere and for all Canadians."

Ambrose also spoke highly of Harper's record of improving Canada's foreign policy, balancing the budget, opening up new markets and protecting the country's most vulnerable populations.

"On behalf of the Conservative caucus and the Conservative Party of Canada, we thank Stephen Harper for his immense contributions, and we wish him well in his future endeavours."

Many residents in Harper's former riding were happy with the job he did for Canada and are sad to see him go.

"He did very well. It's very sad to see him go. As a Prime Minister he did exceptionally well. He did so much for the country. I wish him all the best for the future," said Karen Dickason.

Others say Harper's serious stance when it came to politics served him well but he lacked the popularity to appeal to modern voters.

"Being from here, I think he did a great job. He had some seriousness about the position rather than some of the flakiness that you get now with the more modern politicians," said Fritz Kiesling, "The basis was really good. I guess he lost some support in the end. The flashiness wasn't there, but the politics was."

Another man called Harper the best leader for his generation. "I think in my lifetime that he's been the best Prime Minister we've ever had. He brought dignity to the Prime Minstership, he was well regarded throughout the world and did some great stuff. He wasn't successful in everything, but nobody ever is. For me, he's been the best."

Harper did, however, lose some popularity amongst some new Canadians because of a lack of services, but many say he still worked hard.

"He did his job very well and was good for the economy of Canada," one man said.

Harper served as Prime Minister from 2006 to 2015 when he was defeated by the Trudeau Liberals in October.

He resigned as party leader on the same day he was defeated by Justin Trudeau.

The 57-year-old chose to stay on as an MP for his Calgary riding and routinely showed up for votes in the House of Commons over the last few months.

Harper was first elected as a Reform MP in 1993 and would go on to become the first leader of the modern day Conservative Party in 2003.

Since last fall's defeat, he and his wife Laureen have been living in their Calgary home.

As for the Conservative Party itself, Harper will still have ties, if only just behind the scenes, because he was elected the head of the Conservative Fund of Canada, the party's fundraising arm.

Harper's full statement regarding his resignation from his Facebook page is below:

(With files from The Canadian Press)