This suburban area had leaned Progressive Conservative from 1979 until 1993 when it swung hard to the Liberals primarily due to the rapid growth of the Greater Toronto Area and high immigrant populations, just like the suburbs to the north of Toronto. After winning just one seat (Mississauga East) in 1988, the Liberals swept every seat in this region from 1993 to 2006. The new Conservative Party (replacing the Progressive Conservatives) won their first seats in the area in 2008, picking up Oakville and Mississauga—Erindale before sweeping the region when they formed a majority government in 2011. However, the Liberals swept the region in 2015, and again in 2019. In the 2021 Canadian federal election, the Liberals swept the region again, winning all seats with significant margins - allowing them a strong 160 seat minority.

In 2004, the Liberals won a majority of the vote in every Mississauga and Oakville-based seat, while winning just under 50% in each of the three Brampton-based seats. Their strongest riding was Mississauga East—Cooksville (57%), while their weakest seat was Brampton West (45%). In 2006, the Liberals won a majority of the votes in just three seats, with their strongest seat this time being Mississauga—Brampton South (54%) with their weakest seat being Oakville (43%), which they won by fewer than 800 votes. In 2008, the strongest Liberal seat was again Mississauga East—Cooksville, the only seat in the region where they won a majority of the vote (50%). In 2011 they were shut out of the region, but nearly won Mississauga East—Cooksville, losing it by fewer than 700 votes. In 2015, 2019 and 2021 Canadian federal elections, the Liberals won all ridings in Mississauga, Brampton, and Oakville.

The Conservatives came within 5 points of winning Brampton West, their best seat in 2004, thanks to star candidate Tony Clement. In 2006, their strongest seat was Oakville, which they nearly won. Oakville remained the Conservatives' best seat in 2008 and 2011. When they swept the region in 2011, Oakville was the only riding where they won a majority of the vote (54%). Thanks to a three-way vote split, the Conservatives still won Bramalea—Gore—Malton with just 34% of the vote.

The NDP has traditionally been very weak in the region. Thanks to a strong candidacy of Jagmeet Singh, the NDP placed second in Bramalea—Gore—Malton in 2011, with 33.5% of the vote, losing the riding by fewer than 600 votes.

Votes by party throughout time

More information Election, Liberal ...

Election	Liberal	Conservative	New Democratic	Green	People's	PC	Reform / Alliance	Others
1979	85,030 35.0%	—	39,293 16.2%	—	—	117,225 48.2%	—	1,340 0.6%
1980	95,794 40.7%	—	40,873 17.4%	—	—	97,214 41.3%	—	1,575 0.7%
1984	87,527 29.0%	—	44,927 14.9%	2,561 0.8%	—	165,889 55.0%	—	435 0.1%
1988	118,313 36.1%	—	42,726 13.0%	—	—	159,370 48.6%	—	6,614 2.0%
1993	194,214 51.8%	—	10,214 2.7%	722 0.2%	—	74,984 20.0%	88,722 23.7%	5,644 1.5%
1997	190,798 54.9%	—	18,225 5.2%	—	—	72,276 20.8%	64,975 18.7%	1,429 0.4%
2000	192,872 58.2%	—	12,584 3.8%	3,273 1.0%	—	53,193 16.0%	67,407 20.3%	1,471 0.4%
2004	212,592 51.7%	129,714 31.5%	48,502 11.8%	17,084 4.2%	—	—	—	2,186 0.5%
2006	226,205 47.7%	168,816 35.6%	56,694 12.0%	19,446 4.1%	—	—	—	2,171 0.5%
2008	190,494 43.4%	170,838 38.9%	46,148 10.5%	29,384 6.7%	—	—	—	1,967 0.4%
2011	165,925 33.6%	220,229 44.6%	91,548 18.6%	14,142 2.9%	—	—	—	1,419 0.3%
2015	339,816 51.0%	238,968 35.9%	72,649 10.9%	12,571 1.9%	—	—	—	1,885 0.3%
2019	361,593 50.8%	222,821 31.3%	90,648 12.7%	25,817 3.6%	7,757 1.1%	—	—	1,654 0.2%
2021	312,807 50.1%	207,982 33.3%	75,461 12.1%	6,925 1.1%	19,500 3.1%	—	—	1,863 0.3%

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