Beginning in March 2023, and with increased intensity starting in June, Canada was affected by a record-setting series of wildfires. All 13 provinces and territories were affected, with large fires in Alberta, British Columbia, the Northwest Territories, Nova Scotia, Ontario, and Quebec. The 2023 wildfire season had the most area burned in Canada's recorded history, surpassing the 1989, 1995, and 2014 fire seasons, as well as in recorded North American history, surpassing the 2020 Western US wildfire season.

As of October 6, 6,551 fires had burned 184,961 square kilometres (71,414 sq mi), about 5% of the entire forest area of Canada, and more than six times the long-term average of 27,300 square kilometres (10,541 sq mi) for that time of the year. As of mid-October, the total area burnt was more than 2.5 times the previous record. Eight firefighters were killed, and 185,000 to 232,000 people were displaced, including 16,400 in Nova Scotia's capital of Halifax, 21,720 in the Northwest Territories capital of Yellowknife, and almost 30,000 in British Columbia's Kelowna and West Kelowna. Thousands of international firefighters travelled to Canada to combat the fires.

Smoke emitted from the wildfires caused air quality alerts and evacuations in Canada and the United States. In late June, the smoke crossed the Atlantic Ocean, reaching Europe. Many of the largest fires were under control by July, including fires which had funnelled smoke into the Eastern Seaboard. However, significant fires continued well into the fall season, with several major fires breaking out in September. Moderate-to-severe drought conditions from British Columbia to northern Ontario also continued into fall. Though most of the fires were extinguished by winter, some in northern Alberta and British Columbia continued to smoulder in peat, reigniting the following February and starting the 2024 fires.

The frequency, intensity, and timing of wildfires in Canada have changed over time. In general, since the 1970s and 1980s, the total annual number of wildfires has decreased but the area burned in Canada has increased. Since 1959, the number of large fires greater than 200 ha (490 acres) has increased and the average fire season has become longer by about two weeks. In Canada, wildfire season usually starts in May. The 2023 fires were compared to the 2016 Fort McMurray wildfire and the 2021 Lytton wildfire.

The 2023 fire season was mainly driven by anthropogenic climate change, with temperatures in Canada from May to October 2.2 °C (4 °F) higher than the 1991–2020 average. Warmer and drier weather contributed to drought and desiccated vegetation, making it more flammable. In Western Canada, a drought from 2022 persisted and, along with low winter snowpack, led to dried out soil; in contrast, Nova Scotia and Quebec saw normal soil moisture levels but high temperatures and rapid drying caused a flash drought. Climate change made fire weather twice as likely and 20% more intense in Quebec according to estimates from World Weather Attribution, and made the unusually long nationwide fire season five times more likely.

Roughly half of all wildfires in Canada are caused by lightning; due to climate change, lightning-caused fires are happening more frequently, and lightning strikes are expected to double by the end of the century. In terms of wildfire acreage, lightning-caused fires account for about 85% of land burned. Lightning-caused fires often happen in clusters in remote locations. The other half of wildfires in Canada are human-caused, often unintentionally sparked by things such as discarded cigarette butts, abandoned smouldering campfires, sparks from braking trains, off road vehicles, and land clearing activities. While false claims of arson gained traction on social media, arson is generally a minor cause of wildfires in Canada.

Forest management is also a factor in the wildfires. Because Canada's forest management has focused on fire suppression, dry vegetation has accumulated on the forest floor. Canada has generally stopped performing controlled burns, which help reduce the risk of larger and more dangerous fires. It is difficult to get permission for controlled burns, especially for Indigenous groups who have historically performed them and are disproportionately affected by wildfires. Canada lacks a national firefighting service, and local resources are stretched thin due to budget cuts.

Wind from a passing cold front during the week of May 18 exacerbated the fire risk, as did a concurrent heat wave in the west. Canadian Minister of Public Safety Bill Blair said: "These conditions, this early in the season, are unprecedented. Due to climate change, similar extreme weather events may continue to increase in both frequency and severity across our country."