Johansen has taken a lot of criticism from Bhoys fans for his performances during the first half of the campaign.
However, the central midfielder has started to show signs that he is getting back to his best more recently.
And Griffiths said: "Stefan Johansen has had a tough start to the season but in the last month he has played very well.
"He was one of the best on the pitch, he created a lot and worked really hard.
"He is a top quality player, a player giving a lot of things on and off the pitch to the team and I love having him here at Celtic."
Johansen won Celtic’s Player of the Season award during his first year at Parkhead, but his performances completely tailed off in the early part of this campaign.
The Norwegian scored three goals in his first four matches, but after that initial burst of form he completely lost his rhythm.
Ronny Deila was then criticised by many Celtic supporters for persistently sticking by Johansen, despite his run of poor performances.
However, Johansen has begun to repay his manager’s faith in recent displays and he has shown the form which made him so popular last term.
The 25-year-old will now be hoping to continue to impress, with Celtic’s next fixture coming against Inverness Caledonian Thistle at the weekend.