England winger Johnson has agreed a new deal which keeps him at the club until 2016, while Argentina defender Zabaleta has agreed fresh terms to stay until 2015.
Johnson's deal should end long-running speculation about a move away from the club, with the 24-year-old telling the club's website: "I wouldn't have signed if I didn't see a big future here. I'm delighted to sign, I'm just glad it's all sorted out. It was never on my mind when I was playing. You can't let that happen, contracts can take a long time these days."
He added: "This club's going places and I want to be up there with them at one of the top clubs in Europe.
"I want to become a top player, I want to keep winning things and picking up medals.
"This is such an exciting time to be at the club, things are moving so fast and there's been something new every day in the two years that I've been here.
"It's great being part of it - my game's improved, I'm playing for England and in the Champions League, that probably wouldn't have happened if I hadn't come here."
Zabaleta, an irregular starter but important squad man due to his versatility, was set to be out of contract next year.
"I'm in a very good team, and I try to do my best for the club, the team and the fans," the Argentinian said.
"I didn't think twice, I gave a quick answer because I was so happy to sign."
Source: PA
Source: PA