Nepean-Carleton was a provincial electoral district in eastern Ontario, Canada. It elected one member to the Legislative Assembly of Ontario from 1999 to 2014.

The riding was represented in the Ontario legislature by Progressive Conservative John Baird since it became a provincial riding in 1999 until he resigned in 2005 to run in the 2006 federal election. PC candidate Lisa MacLeod won the provincial by-election to fill the vacancy that was held on March 30, 2006.

Following the 2018 election, the district was dissolved into Nepean, Carleton, Orléans, and Kanata—Carleton.

The riding was created in 1999, to match its federal counterpart. It was made up of 62% of Nepean, 43% of Carleton and 11% of Ottawa–Rideau.

Nepean
Assembly	Years	Member		Party
Riding created from Nepean, Carleton, and Ottawa–Rideau.
37th	1999–2003		John Baird	Progressive Conservative
38th	2003–2005
	2005–2007		Lisa MacLeod
39th	2007–2011
40th	2011–2014
41st	2014–2018
Riding dissolved into Nepean, Carleton, Orléans, and Kanata—Carleton.

v t e 2014 Ontario general election
Party	Candidate	Votes	%	±%
	Progressive Conservative	Lisa MacLeod	30,901	46.77	−7.71
	Liberal	Jack Uppal	21,974	33.26	+6.29
	New Democratic	Ric Dagenais	8,628	13.06	−1.71
	Green	Gordon Kubanek	3,630	5.49	+2.51
	Libertarian	Coreen Corcoran	940	1.42	+1.01
Total valid votes			66,073	100.0	+20.00
	Progressive Conservative hold		Swing		−7.00
Source(s) Elections Ontario (2014). "Official result from the records – 052, Nepean—Carleton" (PDF). Retrieved 27 June 2015.

v t e 2011 Ontario general election
Party	Candidate	Votes	%	±%	Expenditures
	Progressive Conservative	Lisa MacLeod	29,985	54.48	+4.20	$   61,855.47
	Liberal	Don Dransfield	14,844	26.97	−5.97	20,300.63
	New Democratic	Ric Dagenais	8,127	14.77	+7.34	18,039.80
	Green	Gordon Kubanek	1,641	2.98	−5.38	2,855.87
	Libertarian	Roger Toutant	223	0.41		0.00
	Freedom	Marco Rossi	217	0.39		0.00
Total valid votes / expense limit			55,037	100.0	+2.23	$ 131,703.25
Total rejected, unmarked and declined ballots			193	0.35	−0.17
Turnout			55,230	49.91	−4.70
Eligible voters			110,662		+11.69
	Progressive Conservative hold		Swing		+5.09
Source(s) "Summary of Valid Votes Cast for Each Candidate – October 6, 2011 General Election" (PDF). "Statistical Summary – General Elections 2011" ( XLS Spreadsheet). Retrieved May 28, 2014. "2011 Candidate Campaign Returns (CR-1)". Elections Ontario. Retrieved May 31, 2014.

v t e 2007 Ontario general election
Party	Candidate	Votes	%	±%	Expenditures
	Progressive Conservative	Lisa MacLeod	27,070	50.28	−7.29	$   58,239.69
	Liberal	Jai Aggarwal	17,731	32.94	+1.50	35,359.08
	Green	Gordon Kubanek	4,500	8.36	+6.25	3,130.46
	New Democratic	Tristan Maack	4,000	7.43	−0.84	11,543.93
	Family Coalition	Suzanne Fortin	533	0.99		0.00
Total valid votes/expense limit			53,834	100.0	+79.01	$ 107,004.24
Total rejected ballots			277	0.52	+0.20
Turnout			54,111	54.61	+26.09
Eligible voters			99,078		−6.36
Source(s) "Summary of Valid Votes Cast for Each Candidate – October 10, 2007 General Election" (PDF). "Statistical Summary – General Elections 2007" (PDF). Elections Ontario. Retrieved May 28, 2014. "2007 Candidate Campaign Returns (CR-1)". Retrieved May 31, 2014.

v t e Ontario provincial by-election, March 30, 2006
Party	Candidate	Votes	%	±%	Expenditures
	Progressive Conservative	Lisa MacLeod	17,312	57.57	+3.51	$  89,547.03
	Liberal	Brian Ford	9,455	31.44	−4.21	58,560.17
	New Democratic	Laurel Gibbons	2,487	8.27	+1.73	32,687.68
	Green	Peter V. Tretter	634	2.11	−1.65	852.94
	Independent	John Turmel	112	0.37		0.00
	Freedom	Jurgen Vollrath	73	0.24		0.00
Total valid votes/expense limit			30,073	100.0	−48.65	$ 114,226.16
Total rejected ballots			97	0.32	−0.13
Turnout			30,170	28.52	−33.71
Eligible voters			105,802		+11.91
Source(s) "By-Election 2006 – Summary of Valid Ballots Cast for Each Candidate". Elections Ontario. March 30, 2006. Retrieved May 28, 2014. "By-Election 2006 – Poll by Poll Results". Elections Ontario. Retrieved May 28, 2014. "CR-1 Campaign Returns". Elections Ontario. Retrieved May 28, 2014.

v t e 2003 Ontario general election
Party	Candidate	Votes	%	±%	Expenditures
	Progressive Conservative	John Baird	31,662	54.06	−8.25	$ 89,484.81
	Liberal	Rod Vanier	20,878	35.65	+2.45	59,182.48
	New Democratic	Liam McCarthy	3,828	6.54	+3.28	7,619.96
	Green	Matt Takach	2,200	3.76		4,820.88
Total valid votes/expense limit			58,568	100.0	+15.69	$ 90,762.24
Total rejected ballots			263	0.45	−0.13
Turnout			58,831	62.23	+1.21
Eligible voters			94,544		+13.30
Source(s) "General Election of October 2, 2003 — Summary of Valid Ballots by Candidate". Elections Ontario. Retrieved May 28, 2014. "General Election of October 2, 2003 — Statistical Summary". Elections Ontario. Retrieved May 28, 2014. "2003 Election Returns - Candidate and Association" ( Word'95 .doc files /  – 3.05MB). Retrieved May 28, 2014.

v t e 1999 Ontario general election
Party	Candidate	Votes	%	Expenditures
	Progressive Conservative	John Baird	31,546	62.31	$60,150.37
	Liberal	Gord Hunter	16,809	33.20	56,229.71
	New Democratic	Craig Parsons	1,647	3.25	8,231.29
	Freedom	Bill Frampton	386	0.76	0.00
	Natural Law	Brian E. Jackson	239	0.47	0.00
Total valid votes/expense limit			50,627	100.0	$ 80,110.08
Total rejected ballots			294	0.58
Turnout			50,921	61.02
Eligible voters			83,448
Source(s) "General Election of June 3 1999 — Summary of Valid Ballots by Candidate". Elections Ontario. Retrieved May 28, 2014. "General Election of June 3 1999 — Statistical Summary". Elections Ontario. Retrieved May 28, 2014. "1999 Election and Annual Returns - Candidate and Constituency Association Returns". Retrieved May 28, 2014.

2007 Ontario electoral reform referendum
Side		Votes	%
	First Past the Post	36,569	68.5
	Mixed member proportional	16,821	31.5
	Total valid votes	53,390	100.0

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