It means that John Fletcher's side will now face Wales in the semi-final on Tuesday after their victory over Scotland.
Fletcher said: "We're pleased to get the win, and to score ten tries is always pleasing.
"There are areas to work on - but we worked the guys in training yesterday and it was a good blow out for them today. Huge credit to Portugal though, they more than played their part and I thought that they deserved their try."
Wales edged a far closer contest with Scotland, prevailing 23-21 despite having taken a 13-3 at the break thanks to a Jarrod Evans penalty and an individual try for inside centre Daniel Jones.
Wales replacement winger Shaun Pearce helped himself to two tries after the break but Scotland tries from George Taylor and Robbie Nairn ensured for a thrilling finish.
Wales team manager Will Thomas said: "It was a solid first outing. We looked comfortable in the first half and scored some well worked tries but we lost our way slightly at the end.
"We have some bumps and bruises to assess over the next 24 to 48 hours but we will now turn our attentions to preparing for England. We will need to up our game considerably in order to compete with them on Tuesday."
Elsewhere, Ireland came from behind to beat Georgia 20-10 and they will face France, who defeated Italy 29-7 in the final game of the day.