The win moves Canada to the top of Group E, with the Netherlands and New Zealand only scheduled to play on Tuesday.
Canada had 69 per cent of possession in the first half and seven corners to Cameroon's two, but only managed two shots on target to Cameroon's one.
Still in a game short on goals, Cameroon, which changed its formation in search of more offence in the second half, had its chance to pull even. Claudine Meffometou nearly had a replay of Buchanan's goal in the 70th minute but her header off a corner was just wide.
One would be forgiven for handing home advantage to the French national team at a World Cup in France but in a cool Stade de la Mosson in Montpellier, with the sun setting, Cameroon were urged on with more gusto than that on show in the Parc des Princes last Friday, with significantly fewer numbers.
The tests will only get more hard from here, as Canada's next game is against world No. 19 New Zealand on Saturday (12 pm PT / 3 pm ET on TSN). Four Canadian players from that youth team are on this World Cup roster: Jayde Riviere, Julia Grosso, Jordyn Huitema and Deanne Rose. Huitema scored the opening goal in that victory, while Grosso provided an assist on the game-winner in the 83rd minute.
Three of the five goals Cameroon have conceded in the Women's World Cup have come from corners. The No. 1-ranked United States is the defending Women's World Cup champion. There is a reason this team came third behind those two at the African Cup of Nations, they lack cohesion on the pitch.
Canada came into the match with a 1-1-1 record against African opponents at the tournament, having defeated Ghana (4-0 in 2007) and drawn and lost to Nigeria (3-3 in 1995 and beaten 1-0 in 2011). The 21-year-old born in Houston, Texas was a long-time teammate of Canadian players Ashley Lawrence and Kadeisha Buchanan at West Virginia University.
Canada is considered a tournament contender and starting with a win was important for the team. The group features three teenagers (Jayde Riviere, Julia Grosso and Jordyn Huitema) and 12 players in their early to mid-20s.
The Portland Thorns striker did have more efforts in the second half; including another header which failed to trouble the goalkeeper, a poor free-kick which was nowhere near beating the wall, and a close-range stab goalwards that just wouldn't go in. Fifteen of its 23-woman roster play their club soccer overseas - including nine in France. Only the Americans and Brazilians have an older side.
46 - Cameroon's ranking entering the World Cup.
Christine Sinclair is four goals away from becoming the highest ever goalscorer in global football, across both the men and the women's game. This also marks the fifth time she's suited up in a World Cup.
2003 - Christine Sinclair's first ever World Cup goal was scored at the 2003 edition of the tournament. It came in the fourth minute of a 4-1 group stage loss to Germany at Crew Stadium in Columbus, Ohio.