The prolific striker struck either side of half-time and set up David Silva as title-chasing City eased to three Barclays Premier League points in the snow at the Etihad Stadium.
It was the latest encouraging sign that Aguero's form is returning after his most recent injury setbacks, with hamstring and heel problems ruling him out after netting five against Newcastle in October
The 27-year-old produced two ineffectual performances on his return, but h as now scored four in his last five appearances and, with City fighting in four competitions, momentum could be building at a critical time
"He is one of the main players for the team - we need the best Sergio Aguero week in, week out," right-back Zabaleta, who is also finding his way back to fitness after a knee injury, said.
"There is a still a long season to go and this is a crucial period for the team
We know we are involved in the four competitions.
"Hopefully he can continue in this way and be 100 per cent fit until the end of the season
If he continues being that clinical, I am sure we will have a lot of chances to win games."
City actually made a sluggish start against a Palace side without a goal in their four previous league games
Damien Delaney headed an early chance at Joe Hart and shot over after a mistake by the goalkeeper and Scott Dann also had a free header.
But once City had taken the lead through Fabian Delph's long-range strike in the 21st minute - for which Wayne Hennessey might have done better - they did not really seem in danger
Aguero doubled the lead before the break and then tapped in a third after 68 minutes.
He might have completed a hat-trick after breaking from inside his own half late on, but selflessly passed up the chance to allow Silva to complete the scoring.
Zabaleta, who racked up his 200th Premier League appearance on his 31st birthday, said: "It was a great day, especially because I also came back for a Premier League game
I've been a long period without a game in the Premier League
"I am very happy for the performance of the team
It is three important points after we dropped two points last game against Everton
It is a huge win."
Palace boss Alan Pardew was not too disappointed with his side's performance, although the result continued their recent slide.
The Eagles remain eighth in the Premier League, but have not won a top-flight match since December 19 and now lost three in succession
"I can't remember a team playing so well here and getting that scoreline," Pardew said.
"We didn't do much wrong, we played well
It's hard to take but there were a lot of things I was pleased with."
One of the encouraging aspects was the return of striker Connor Wickham to the starting line-up for the first time in almost a month, but Pardew has not ruled out signing another forward before the end of the month.
"Maybe we do need to bring another striker in," he told TV reporters
"That would give us all a boost I think.
"We will just have to see how it goes but five games without a goal is a statistic we don't want."
Source : PA