The result ended Ipswich's 21-match unbeaten home run and gave Liverpool their first league win of the season. It also prevented the Reds from going seven games without a victory for only the second time in their history.
Liverpool had yet to lead in a match this season, but they wasted little time changing that.
Cody Gakpo sent Isak through with a clever pass in the sixth minute and the Sweden international made no mistake, firing the ball past Kjell Scherpen at the near post.
Three minutes later, Isak struck again.
This time he collected a superb outside-of-the-boot pass before working his way past Jacob Greaves and calmly finishing beyond Scherpen to put Liverpool firmly in control.
The hosts struggled to cope with Liverpool's attacking threat and Isak almost completed his hat-trick before half-time, only for his effort to be ruled out for offside after a precise pass from Florian Wirtz.
Ipswich did have chances, with Leif Davis heading wide at the back post, but Liverpool continued to look the more dangerous side.
Dominik Szoboszlai tested Scherpen several times from distance, while Alexis Mac Allister headed straight at the goalkeeper from a corner early in the second half.
Isak was withdrawn shortly after the hour mark, bringing an end to an impressive performance.
That allowed new signing Bradley Barcola to make his Liverpool debut after completing a reported 123 million-pound move from Paris Saint-Germain earlier in the week.
The France international immediately showed glimpses of his pace and ability, producing a dangerous run after coming off the bench.
Liverpool head coach Andoni Iraola was pleased with Barcola's contribution but warned supporters not to expect too much too soon.
"I think Bradley hasn't played a single minute since the World Cup so we needed to be careful," Iraola said.
"I have seen him training well, in a good place. I think he has helped us."
Iraola felt Barcola could have been involved even more in Liverpool's attacking play but was encouraged by what he saw.
"He had a very good counter with a pass inside which Cody finished but we didn't score. He was always a threat," he said.
"When he carries the ball, I think you can feel this threat."
Iraola added that Barcola's 30 minutes on the pitch would be useful as he builds up his fitness.
"I'm happy because I think 30 minutes is going to be good for his fitness and his build-up," he said. "It will continue because we play a lot of games so he will have the chance to play more."
The Liverpool boss also stressed that Barcola has had little preparation for the new campaign.
"He hasn't played any pre-season minutes," Iraola said. "The demands of the games are always very different to training and we have to be aware of this."
For Ipswich, the defeat was another difficult reminder of the demands of Premier League football. After their impressive opening win against Sunderland, they have now lost their last two league matches by a combined 7-2 scoreline.
Liverpool, meanwhile, extended their unbeaten run against newly promoted sides to 21 matches, with 16 wins and five draws.
The Reds now turn their attention to Europe, with Atletico Madrid visiting Anfield in the Champions League on Wednesday.