A Sergio Aguero-inspired City swept aside the Cottagers to maintain its 100 percent home record in the League in wintery Mancunian conditions after suffering defeat at Everton in mid-week.
The England winger also had one of his better games of the season, winning a penalty for City's opener and firing in a cross that was deflected in by Chris Baird's for his side's second.
"It was obviously important to bounce back and get a good result today, especially at home and play like we know we can," Johnson told ESPN. "It was most important that we got the three points today and we did that."
Edin Dzeko netted City's third and final goal and the Bosnian is keen to get amongst the goals to boost the Citizens' goal difference, which is already slightly greater than Manchester United's at the top of the Premier League.
"I think every goal is important and the goal difference is really important," Dzeko said. "We are three points ahead of United now and they have a tough game tomorrow [away at Chelsea] so now we will wait and see what happens."