Wales extended their lead over Fiji with a penalty try just before half-time.
Referee Pascal Gauzere awarded the try after the visitors twice infringed when a Welsh maul was approaching the line.
Fiji prop Campese Ma'afu was sent to the sin bin.
Nemani Nadolo had kicked two penalties to narrow the scores, after Wales' strong start.
The South Sea Islanders looked very dangerous in open play, and gave up a clear chance to score a try, when visiting captain Akapusi Qera ignored a two-man overlap and was tackled.
Wales lead Fiji 10-0, thanks to two tries in the first quarter of their autumn international at the Millennium Stadium.
The hosts went ahead after six minutes. George North touched down in the corner after the forwards made ground with a maul, and the backs ran intelligent lines to create space.
Fly-half Rhys Priestland presented Fiji with a chance when the ball slipped out of his hands, but visiting winger Waisea Nayacalevu knocked on with the line in sight.
Wales extended their lead with another try after 19 minutes, spreading the ball wide from a ruck, before Alex Cuthbert beat his man to score.
Wales face Fiji at the Millennium Stadium this afternoon, desperate to get an autumn international victory in the bank, and make a statement ahead of next year's World Cup.
They will face the South Sea Islanders again next October, in a difficult pool that also includes England and Australia.
Warren Gatland has made eight changes to his Welsh side that lost 33-28 to Australia last weekend, with James Hook back on the bench.
Read More: Full Wales squad to face Fiji
Wales' previous meetings with Fiji have been far from predictable.
Gareth Jenkins' side were dumped out of the 2007 World Cup by a shock 38-34 defeat.
Wales under Gatland managed only a 16-16 draw at the Millennium Stadium in the 2010 autumn series.
Revenge was finally had at the 2011 World Cup, with Fiji on the end of a 66-0 hammering.
Wales gave their blessing for hooker Richard Hibbard to be on the bench for Gloucester last night, according to the club's director of rugby.
Hibbard played the last seven minutes against Harlequins, despite not being considered to play for Wales against Fiji today, after injuring his ankle against Australia last weekend.
Yesterday, Wales forwards coach Robin McBryde said that if Hibbard "does take the field of play, then obviously he jeapordises his inclusion" for Wales' autumn international against New Zealand next week.
After the game last night, Gloucester director of rugby David Humphreys said: "We did not have any problems with Wales. We had discussions with the Welsh management yesterday and it was agreed with the Welsh management that Richard would be sitting on the bench. We are unaware of what changed between last night and this morning."
"The starting point in all these discussions is we wouldn't do anything that jeopardised player welfare and, as far as we were concerned, Richard was fit to play and that was agreed with the Welsh management yesterday afternoon."
"We are very surprised by this. As far as we are concerned, there was no issue. I don't think this is something which should have been made a big issue."
A spectator at Saturday's meeting between England and New Zealand wrote a letter to a newspaper claiming to have witnessed the abuse.Read the full story ›
Wales have made eight personnel changes to their side to face Fiji on Saturday.Read the full story ›
Wales have called Gloucester fly-half James Hook into their Dove Men Series squad.
It follows Dan Biggar picking up an injury against Australia.
Hook will link up with the squad later today when they gather to prepare for Saturday's clash against Fiji.
No players have been released from the squad.
Both Wales and Australia deny a psychological blow has been struck after the Wallabies registered a tenth straight success over Wales in a 33-28 win in the opening game of the Autumn Series.
Saturday’s opening game of the 2014 series was the last time the sides will meet before they go head to head in their World Cup 2015 pool – a pool which also includes England and will only see two teams progress to the knockout stages.
Australia’s winning run stretches back to 29th Nov 2008 although recent meetings have left little to choose between the sides – the last five meetings have all ended with scores of five points or less between them.
But that record means little according to both camps for what they say will be a completely different encounter in terms of form, preparation and atmosphere.
“When we face them in the World Cup it’s a different beast, a different animal that’s going to be facing them in that pool game’ said Wales coach Warren Gatland.
‘Our time together will be a big upward curve and we’ll continue to get better. There’s a lot of things we’ve prioritised in this campaign and there’s some things we didn’t cover.
‘I can come away from that and say there’s a big tick in a lot of things to continue to work on and knowing the way we’ve prepared I’m feeling confident that we’ll get better as this campaign goes on. ‘
The 28-33 defeat saw a flurry of first half tries before Australia fly half Bernard Foley tipped the game in the visitors favour with a drop goal in the 73rd minute, before a kicking third penalty to leave the game out of Wales’ grasp.
So with Wales so close yet so far once again does a tenth straight defeat leave a scar ahead of next year’s World Cup?
‘No it doesn’t’ according to Wales captain Sam Warburton.
‘It’s the best game that we’ve started in an autumn, or a Six Nations campaign for that matter, for quite a long time I think. I can’t remember starting that well.
‘Everyone knows in the squad and the management that we’ve got the ability to beat these teams. They’re not going to be consistently this close for the next nine or ten matches and not go our way one time. It’s just a matter of when, not if.
‘I think going in on Monday it will be a lot more positive. There was a heck of a lot of good from that game.
‘I think when we do have a look at the tape I think they’ll be a lot of pleasing signs from that game.
So with Wales not willing to loiter on another Australian disappointment it is left to the Wallabies themselves to rub salt into the ten game long wound. But not so, at least from newly installed Head Coach Michael Cheika who insists no momentum will lie with his side when the teams meet at Twickenham. It is not, he says, round one to the Wallabies.
“No. Not at all.
‘I’ve said several times that I’ve never been to a rugby game that you’ve played in and it’s had an influence on a game that’s going to be played ten months later. It’s a totally unique occasion.
‘We won today. It’s great. The guys worked hard and our next focus is to get on a try and beat the French.
‘If we start thinking about that game there we’re only going to lose the games in between.
‘We’ll just concentrate on paying well, doing our bit, and when that game comes, we’ll do our best again.
Leigh Halfpenny and Dan Biggar are both doubts for next week’s second game of the autumn series against Fiji in Cardiff after injuries forced them out of Wales 33-28 defeat to Australia.
Halfpenny left the field after what Head Coach Warren Gatland described as a ‘knock’ to his head in the build up to Wales third try.
Gatland however stressed that the decision to remove him from the game was only precautionary and a full concussion assessment will be made after the match.
Biggar limped off in the second half of the game at the Millennium Stadium with a groin strain, the extent of which is yet to be disclosed, but looks likely to keep him out of action for several days.
Warren Gatland said both players will be assessed when the side meets up on Monday but that he will look to call up another fly half as cover for Biggar.
"We’ll have to sit down as a group and bring another 10 in next week...We’ll have to see how the next 48 hours go (for Leigh Halfpenny), probably a cog’ test for concussion just to see how he goes but probably for that it’s just a opportunity for us to give him a rest next week anyway."
Wales head coach Warren Gatland has given his reaction to Wales' 28 - 33 loss against Australia.
"It's frustrating" he said.
"I'm not happy with the result, but I'm pretty happy with the performance... the way we played and how positively we played"
"I thought we showed a huge amount of positives we need and something we can build on for the rest of the campaign".