That was a 1.1 percent increase in seniors from the last census in 2006 and reflects on the most recent population estimate in January of 34.6 million people.
The share of the working-age population in Canada was 68.5 percent in 2011, while the share of children aged 14 and under fell from 17.7 percent in 2006 to 16.7 percent in 2011, the report said.
"The main factors behind the aging of Canada's population are the nation's below-replacement-level fertility rate over the last 40 years and an increasing life expectancy," StatsCan said.
The number of people age 100 or older also increased to 5,825 in 2011 from 4,635 in 2006, the census said.
Regionally, Alberta had the lowest proportion of seniors at 11.1 percent. Proportions in Yukon, Northwest Territories and Nunavut were also much lower than the national average.
Exploding whale video goes viral on Internet
'SNL': 'Anchorman 2' cast, One Direction sing 'Afternoon Delight' [VIDEO]