The City defender suffered a groin injury in October and was in a race to be fit for the World Cup with England after surgery to his left leg.
After joining up with the Three Lions and playing a big part in Qatar, Guardiola says that Walker has had some niggles since his return.
But without a Premier League start since the 6-3 victory over Manchester United at the start of October, the City boss says he is ready to make a big impact between now and the end of the season.
“Yesterday he made the first good training session since coming back - he had niggles, some problems and he could not train,” Pep said ahead of the Premier League clash at Chelsea.
“Yesterday was the first time I saw the Kyle I know.
“He didn’t play for a long, long time with us. Of the last 34 games I think he played 11 so that’s a long time out.
In our three matches since the end of the World Cup, Rico Lewis has been outstanding in the right-back role.
Guardiola praised the 18-year-old for the brilliant way that he coped with the pressure at such a young age and says he will also be a big help in the upcoming months.
“We need Kyle back as soon as possible, at his best,” the boss added. “Definitely, we need him. Rico is not going to solve the problems, Rico is going to help us.
“You know what Kyle can do because he has shown it for a long, long, long time. The young players have to help the other ones, we cannot put it on Rico’s shoulders.
“But Rico has shown you can put a lot of pressure on his shoulders because he reacts very well.
“We cannot forget how he played against Chelsea in the Carabao Cup, against Liverpool in Carabao Cup and played [against Leeds] at Elland Road and in the last game [against Everton] he played really good against a tight team and he moved really well.”
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Meanwhile, Guardiola has told striker Erling Haaland to prepare for another battle against Chelsea when he will face defenders Thiago Silva and Kalidou Koulibaly on Thursday night.
The City forward had a physical tussle with Everton’s defenders throughout the 1-1 draw on Saturday and Guardiola was happy with the way he responded.
“I liked it,” he said. “Just [take it] to the limit, not him everyone.
“The decision is he always has to use [his head] but play with this passion and that is necessary. I prefer that than to be flat.
“Central strikers have to handle the tough, tough central defenders and it is necessary tomorrow have a battle with Koulibaly and Thiago Silva.
“Always it’s a big challenge - that’s why the Premier League is so special.”
