The French midfielder was a key component of the Leicester side that shocked the world during the 2015/2016 season as they won the Premier League under Claudio Ranieri.
The 25-year-old subsequently moved to Chelsea in the summer transfer window for a big money fee of £30m ($37.3m) and has flourished under Antonio Conte as the Blues currently sit top of the table with 60 points from 25 games played.
Meanwhile, the Foxes have underwhelmed, languishing just above the relegation zone in 17th place with 21 points from 25 games, resulting in Ranieri's recent sacking.
Ahead of Liverpool's visit to the King Power stadium on 27 February, Wijnaldum believes Kante's departure is one of the reasons Leicester have struggled.
"Of course they have a bad run this season, they are not doing that well compared to last season," the Dutchman said as quoted on Sky Sports. "But I think they are still a good team, almost all the players stayed."
"Kante is a big miss for them, because he was a really important player in the midfield, and he keeps everything together and he was one of the main reasons they were champions last season. And because he left, it makes it way more difficult for everyone in the team.
"But I think they still have a good team and it is still difficult to beat them. You could see that when they played Man City, they had a good game, so they can also win against big teams.
The former Newcastle player also warned his Liverpool teammates not to be complacent against a Leicester side that will be even more desperate for points, as they sit just one point above the relegation zone.
"In the Premier League, almost everyone is difficult to beat, it depends on how you begin a game and how you play in the game," Wijnaldum added. "Now they are at the bottom of the league, but everyone knows they can do better than what they show right now. They showed it last season, so it is difficult to say where they really stand."
"One thing is for sure, they are a good team and a difficult team to beat and that is something we must keep in mind. We cannot win this game on 90 per cent, we have to give 100 per cent to win this game.
"We are running out of games now and the teams at the bottom of the league want every chance to collect points to stay safe. So that can be different to if you had played them at an earlier stage. I think they will fight more now to collect points to be safe earlier."