Ottawa West—Nepean (French: Ottawa-Ouest—Nepean) is a federal electoral district in Ontario, Canada, that has been represented in the House of Commons of Canada since 1997.

The district includes the neighbourhoods of Shirleys Bay, Crystal Beach, Rocky Point, Bayshore, Britannia, Britannia Bay, Lincoln Heights, Whitehaven, Glabar Park, Queensway, Kenson Park, Redwood, Graham Park, Qualicum, Leslie Park, Briargreen, Centrepointe, Woodroffe, Bel-Air Park, Bel-Air Heights, Braemar Park, Copeland Park, Navaho, City View, Ryan Farm, Skyline, Fisher Heights, Parkwood Hills, Carleton Heights, Fisher Glen, Borden Farm, Crestview, Meadowlands, Woodpark, and the western half of Carlington in the City of Ottawa.

The electoral district was created in 1996 from Ottawa West, Nepean and part of Lanark—Carleton ridings.

The 2012 federal redistribution saw the riding gain a small portion from Ottawa Centre, but it remained largely unchanged.

The 2022 Canadian federal electoral redistribution resulted in several boundary changes to the riding.

The eastern riding boundary along Merivale Road was pushed further east to Fisher Avenue. As a consequence, the entire Carlington neighbourhood (not just the western portion) is now part of the riding.

The north-east boundary has also been shifted east, from Maitland and Sherwood Avenues to Golden Avenue and then along Carling Avenue to the 417 Highway. Consequently the McKellar Park and McKellar Heights neighbourhoods have been reassigned from the Ottawa Centre riding into Ottawa West—Nepean.

A small corner of the riding between Merivale Avenue on the West and the Rideau River on the east, and from the railroad tracks in the north to West Hunt Club Road in the south, has been moved from Ottawa West-Nepean to Nepean. While largely retail-commercial in nature, it includes a number of residential homes along or near Prince of Wales Dr.

The north-west boundary has been moved east from Hertzberg Road to Davidson Side Road north of Carling Avenue. That portion has been moved into the Kanata (formerly the Kanata-Carleton) riding. It is a rural area which includes a large area of Federal lands, and so is of small consequence to elector counts.

According to the 2021 Canadian census

Ethnic groups: 60.7% White, 8.9% Black, 7.0% South Asian, 5.3% Arab, 4.6% Chinese, 4.1% Indigenous, 2.2% Southeast Asian, 2.0% Filipino, 1.4% Latin American, 1.4% West Asian

Languages: 60.3% English, 6.5% French, 4.2% Arabic, 2.0% Mandarin, 1.7% Italian, 1.4% Spanish, 1.2% Somali, 1.2% Cantonese, 1.1% Vietnamese, 1.0% Tagalog

Religions: 49.3% Christian (26.3% Catholic, 4.0% Anglican, 3.7% United Church, 2.3% Christian Orthodox, 1.3% Pentecostal, 1.0% Presbyterian, 10.7% Other), 10.8% Muslim, 3.3% Hindu, 1.8% Jewish, 1.5% Buddhist, 31.5% None

Median income: $42,800 (2020)

Average income: $55,900 (2020)

This riding has elected the following members of Parliament:

Parliament	Years	Member		Party
Ottawa West—Nepean Riding created from Ottawa West, Nepean and Lanark—Carleton
36th	1997–2000		Marlene Catterall	Liberal
37th	2000–2004
38th	2004–2006
39th	2006–2008		John Baird	Conservative
40th	2008–2011
41st	2011–2015
42nd	2015–2019		Anita Vandenbeld	Liberal
43rd	2019–2021
44th	2021–present

In the 2004 federal election, Marlene Catterall defeated Conservative Party candidate Sean Casey in a very close election.

In the 2006 federal election, Catterall stepped aside, and high-profile Progressive Conservative Member of Provincial Parliament, John Baird, contested and won the riding for the Conservative Party.

Until February 3, 2015, he was a member of the cabinet of Prime Minister Stephen Harper as Minister of Foreign Affairs. He has also previously served as President of the Treasury Board, then Minister of the Environment, then as Government House Leader. Baird resigned from the House of Commons on March 16, 2015.

Riding associations are the local branches of national political parties:

Party		Association name	President
	New Democratic	Ottawa West—Nepean Federal NDP Association	Stephen Yardy
	Liberal	Ottawa West—Nepean Federal Liberal Association	Christie Boyd
	Conservative	Ottawa West—Nepean Conservative Association	Craig Armstrong
	Green	Ottawa West—Nepean Green Party	David Stibbe
	Christian Heritage	CHP Ottawa West—Nepean	David Darwin