The NOHP had its roots in the April 1973 provincial budget, in which the Government of Ontario proposed to extend the seven per cent provincial sales tax to heating and electricity. Deibel notified the local media that he would go to jail before paying the tax. This led to a meeting of about 500 people, and the formation of a tax repeal committee chaired by Deibel. The committee collected 24,000 signatures from all over Northern Ontario on a petition, and the government ultimately withdrew the proposal.

On May 16, 1973, Deibel formed a committee to discuss this idea, and began research about Northern Ontario’s problems. Deibel travelled Northern Ontario recruiting 600 members for the new province committee, and obtaining 6,000 signatures on a petition requesting that a vote be given to Northern Ontario on the question of forming a new province.

In October 1974, Deibel pitched a tent at Queen’s Park, site of Ontario’s legislative assembly, for three days, and gave interviews to the media. This led to a half-hour private meeting with Premier William Davis, who refused to allow a plebiscite.

In the spring of 1975, Deibel wrote to Premier Davis, offering to abandon the new province committee if the government met seven demands:

1. Establish a Northern Ontario Development Commission with citizens from Northern Ontario.
2. A program paid for by the province to eliminate municipal taxes for ten years for all new manufacturing plants that complete at least 80 per cent of finished form.
3. Non-renewable resources to have a depletion tax deposited in a trust fund designed for that area when the project in finished.
4. At least 50 per cent of all natural resources to be processed and manufactured in Northern Ontario.
5. A billion-dollar catch-up program to provide serviced land for housing industrial parks and social needs.
6. Appointment of a provincial cabinet minister with full responsibility for mining.
7. Lakehead University and Laurentian University would receive funding for a continuing program of research and development that assures a better quality of life in Northern Ontario.

The Ontario government responded to the offer, noting that “Northern Ontario… is strengthened by being an integral part of a very broadly based provincial economy.” The government’s response addressed each of the demands, but accepted none of them.

Deibel replied with a demand for the Premier’s resignation, and on September 17, 1976, began to collect the 10,000 signatures necessary to register a new political party. The Northern Ontario Heritage Party was given official certification in October 1977, with 10,600 signatures. The provincial government subsequently created the Ministry of Northern Development and Mines in 1977.

Deibel was succeeded as leader by Garry Lewis, a businessman from Callander who dropped separation from the party’s agenda and instead campaigned for economic development of the region within the province.

Despite the more than 10,000 people who had signed the party’s original certification documents, the party had no more than 200 paying members at its peak.

In early 1983, the party membership ousted Lewis and its executive. The party’s new leader, Ronald Gilson, promptly reinstated separation from Ontario as the party’s primary goal. By 1985, however, the party was deregistered after failing to file its annual contributions and expenses return for 1984; Don Joynt, the executive director of the provincial Commission on Election Contributions and Expenses, revealed that in its year-end return for 1983, the party had listed just ninety cents in assets and only four card-carrying members.

In 2010, Deibel began trying to revive the party, setting up a website where Northerners were invited to join the party. On August 6, 2010, the party was registered by Elections Ontario.

In its initial platform, the revived Northern Ontario Heritage Party called for a number of measures to increase the region’s power over its own affairs within the province, including increasing the number of Northern Ontario electoral districts in the Legislative Assembly of Ontario and the creation of a special district for the region’s First Nations voters. In its current platform, however, the Northern Ontario Party has returned to advocating for full separation of the region from the province.

The party ran three candidates in the 2011 provincial election, garnering 683 votes. However, one of its candidates ran in the downtown Toronto riding of St. Paul’s rather than in a Northern Ontario riding.

In the 2014 provincial election, the party received 892 votes with three candidates. Deibel ran as the party’s candidate in Thunder Bay—Atikokan.

In 2016, the party was reincorporated as the Northern Ontario Party, under the leadership of Trevor Holliday. Holliday, previously a bus driver for Ontario Northland, was converted to Northern Ontario separation when the government of Dalton McGuinty announced plans in 2012 to shut down the service, and attracted media attention early in 2016 when he created an online petition on change.org which eventually attracted over 4,000 signatories. Deibel remains involved in the party executive.

In 2017, the party called for the creation of a separate Ministry of Natural Resources and Forestry for Northern Ontario as an interim step during the period of secession negotiations, as well as calling for a referendum to revise the province’s school board structure.

Trevor Holliday resigned as party leader in April 2019, in order “to ensure we continue to be able to communicate with the members, media and most importantly Northerners in more than just English.” Shawn Poirier was appointed Interim Leader, with a leadership campaign to be set following the 2019 General Meeting.