While the riding's boundaries (mainly to the south and west as the north and east borders have remained the Ottawa River and Rideau River, respectively) have changed over the years to account for population changes, the riding has always comprised the central areas of Ottawa, the nation's capital.

The 1987 redistribution saw the riding expand westward to Island Park Drive, while losing all of its territory south of the Rideau River.

Following the Canadian federal electoral redistribution, 2012, there was a minor change in the riding's southwestern boundary, which was moved from the former city limits to Baseline Road and Fisher Avenue.

This was somewhat compensated for by changes in the riding's southern boundary, which pushed south and east of the Rideau River for the first time following Bank St and the railway line north of Heron Rd.

The riding was left vacant by Prime Minister Paul Martin until the 2004 election when Ed Broadbent, a former leader of the NDP, defeated Liberal Richard Mahoney, a high-profile lawyer and Liberal strategist and long-time ally of former Prime Minister Paul Martin.

The other candidates in 2004 were Mike Murphy of the Conservatives, David Chernushenko of the Greens, Louis Lang of the Marxist-Leninists, Michael Foster, Stuart Ryan of the Communists, Robert Gauthier, and Carla Marie Dancey.

From the Rideau River, the riding stretches west encompassing the neighbourhoods of Downtown, Centretown (Centretown West which includes Little Italy is usually considered a distinct neighbourhood), LeBreton Flats, Civic Hospital, Mechanicsville, Hintonburg, Wellington Village, Westboro, eastern part of Carlington, Highland Park, and McKellar Park.

Ethnic groups: 72.4% White, 5.5% Black, 4.5% Chinese, 4.1% South Asian, 3.8% Indigenous, 2.4% Arab, 1.7% Southeast Asian, 1.4% Latin American, 1.0% West Asian Languages: 67.0% English, 9.1% French, 1.9% Arabic, 1.8% Mandarin, 1.5% Spanish, 1.1% Cantonese, 1.1% Italian Religions: 42.2% Christian (22.9% Catholic, 4.4% Anglican, 3.4% United Church, 1.8% Christian Orthodox, 1.0% Presbyterian, 8.7% Other), 4.8% Muslim, 2.0% Jewish, 1.4% Hindu, 1.3% Buddhist, 46.9% None Median income: $54,800 (2020) Average income: $77,800 (2020) The Ottawa Centre riding has the highest percentage of master's degree holders in all of Canada (12.7%)[4] In the 2015 election, the riding had the highest turnout in the country with just over 82% of electors casting a ballot in the election.

The seat was vacated in September 2003 when Liberal incumbent Mac Harb received his patronage appointment to the Senate of Canada from outgoing Prime Minister Jean Chrétien.

[15] Paul Martin loyalist Richard Mahoney won the Liberal nomination and expected to win the riding.

In the end, Broadbent won a strong victory, and subsequently announced his retirement the following year, in April 2005.