Johnson is expected to retain his spot on Wednesday when Fulham visit Anfield in the Barclays Premier League.
"Glen Johnson has been fantastic in the left-back position in the past three games. I don't recall anyone going past him," Dalglish said.
"For me, he's doing us a favour. It's not really his chosen position. But he hasn't said a word against it, it's been no problem and he's just gone out and played.
"That's great and I think it just reflects his commitment and his attitude. The fact he is playing there and doing so well is a great credit to him. Also, he'll be thinking that Martin Kelly has done well (at right-back) and it would be unfair on him to leave him out."
Dalglish welcomes back Steven Gerrard insisting the club captain fully deserves a place among Liverpool's legends. Gerrard has served a three-match suspension following his sending-off in the FA Cup defeat by Manchester United.
That tie was Dalglish's first game in charge after he was installed as caretaker-manager until the end of the season following the departure of Roy Hodgson. And he is delighted to be teaming up with Gerrard again - a player he believes would have spanned the generations with his ability in midfield.
Dalglish said: "He is a special person - he's not just a special footballer. The way he has served this club and what the club means to him - it is nothing short of fantastic. He's served this club unbelievably well and we will certainly ride along on the back of that.
"I don't have words in my vocabulary to be complimentary enough about Steven other than to say this club is much better off with him than it could be without him.
"Certainly he's more influential wearing a red shirt more than any colour. He deserves to be up there in the folklore and the history of the club. He is a fantastic footballer that we're very lucky to have at our disposal."
Source: PA