On a day when the league's bottom three teams all won, former Rovers striker James Hayter tucked away a second-half penalty to hand Yeovil a first home victory since December and reduce the gap between the two sides to five points.
Johnson believes the win has dragged both Doncaster and Millwall back into the Championship survival fight.
He said: "It's important when you're near the bottom of the league that you keep your shape and create chances, and we did that.
"We deserved the win. One-nil is a bit hairy-scary, and looking at today's results it was important we stayed in touch. The result has brought Millwall and Doncaster closer to us.
"It wasn't pretty but it's not easy to play on that pitch at the minute with all the rain we've had. Everyone put a shift in and credit to the team - they deserve it.
"A lot of decisions have gone against us in recent weeks, but the referee has done his job today for us.
"Opposition teams who get beat always have a little moan about decisions, but that shows how important they thought today's game was.
"If James (Hayter) gets an opportunity you know he's clever enough to tuck it in the corner.
"That's why he's done so well for us and scored so many goals over the years. He's a great asset and a calming influence for us."
Doncaster manager Paul Dickov claimed his side should have also had a second-half penalty after Yeovil defender Byron Webster appeared to tangle with Bongani Khumalo.
Dickov said: "I thought it was a scrappy game. The conditions and the pitch didn't help us play the way we wanted.
"We've created two or three great chances when we were on top in the second half before their penalty, and it's a completely different outcome if we put them away.
"I've not seen the penalty but at the time I thought it was correct. James (Husband) hasn't made any real complaints about it.
"I felt we should have also had a penalty. I'm not an advocate of players getting sent off, but their lad has swung his arm and smashed Bongani (Khumalo) in the face.
"The referee has seen it and did nothing about it, and the fourth official tells me the decision wasn't given because it was open-handed.
"I was disappointed with the chances we gave away because we've defended well recently.
"It's difficult when a team is one-nil up and you're chasing because you leave yourself open a bit, but our quality in the final third wasn't there today."