First-half goals from captain Casey Stoney and Jill Scott put the home side in the driving seat before Steph Houghton made it 3-0 with a fantastic strike.
Stoney broke the deadlock with an early close range effort and Everton midfielder Scott finished a smart team move after 23 minutes to double her side’s lead.
Houghton was on hand to score her second goal of the tournament with a drive from the edge of the box to put the gloss on a deserved win and continue her side’s quest for gold.
Hope Powell’s side opened their Olympic campaign with a 1-0 win over New Zealand and it took the unchanged home side 17 minutes to make the breakthrough through captain Stoney.
After Christine Manie upended Kim Smith beside the touchline, Scott‘s weighted free kick evaded the Cameroon defence and Lincoln Ladies defender Stoney was on hand to slot home at the back post.
Scott turned from provider to finisher six minutes later as Team GB doubled their lead to put Hope Powell’s side within touching distance of the last eight.
A smart back heel from Kim Little inside the box allowed the Everton midfielder the time and space to pick her spot and calmly steer the ball past Ngo Ndom from 12 yards.
Team GB cranked up the pressure before the half-time whistle but Ngo Ndom spared her side’s blushes with excellent saves from Smith and Little to keep the score down.
The home side started the second half with the same momentum with which they finished the first, and Cameroon substitute Medoura had to be alert to clear an Anita Asante header off the goal line.
Head coach Powell spoke of her concern at containing Cameroon’s unorthodox style and at times the African side looked distinctly below standard.
Both Asante and Ifeoma Dieke left the action through injury as the opponents’ somewhat careless tackling started to take its toll on the Brits.
After a somewhat uneventful 15 minute period, Little again threatened the Cameroon goal on the 71st minute with Team GB’s first real effort but Ngo Ndom was equal to it.
And the keeper had to be at her best to deny Little once more with an acrobatic save to deny the Arsenal midfielder, before Houghton sealed the win with her thunderous 81st minute strike.
Little showed remarkable composure in the box to lay the ball off to Houghton and the Arsenal midfielder drove home her second goal of the tournament.
Little produced a sparkling performance to help her side overcome the tricky Cameroonians and much of Team GB’s work went through the creative midfielder.
British coach Hope Powell said afterwards: "We are happy to win the game. They were very physical and quick but we were disciplined and we executed all three goals well."
Reigning champions the United States and world champions Japan also sealed their places in the quarter-finals, with medal hopefuls Brazil and Sweden joining them.
North Korea had a chance to make the last eight but lost it when they were crushed 5-0 by France at Hampden Park after conceding four goals in the last 20 minutes.
Japan's 0-0 draw with Sweden in Coventry, combined with other results later in the day, meant both qualified from Group F, at worst as one of the two best third-placed teams in the three group competition.
The top two teams in each group qualify, along with the best two third placed finishers.
The United States, bidding for a third successive gold, also won 3-0 against Colombia in Group G in Glasgow while Brazil, bidding for a first Olympic football gold, beat New Zealand 1-0 at Cardiff in Group E with another goal from Cristiane, whose overall tally of 12 is an Olympic all-time scoring record.
And although Japan were held by Sweden, who themselves are hoping for a medal, both are assured of a last eight place as they both have four points from their two matches and will either finish first, second or third in the group.
The third placed team in Group E cannot finish with a better record than either of them, so they are through.
Canada, beaten by Japan in their opening match, rekindled their chances of advancing with a 3-0 win over South Africa.
The US followed up their opening win against France with a solid performance against Colombia with goals from Megan Rapinoe, Abby Wambach, with her 140th international goal, and Carli Lloyd, with the last two goals coming in the last 16 minutes.
The women's competition, unlike the men's, is open to players of all ages with the top two from each of the three groups and the best two third placed teams going into the knockout stages.