The Lions ended their eight-game winless run in the Championship as Shittu headed in on 55 minutes to separate the teams at The Den.
Following a lengthy spell on the sidelines with an Achilles injury, Holloway believes that the Nigerian deserved his goal against the Bluebirds.
"I don't want Danny having to score the winner, that's what my forwards should be doing so I need to have a word with them," he told Sky Sports News.
"But it was nice for him to go up and whack one in with his head. He's very special and I'm delighted he's on the mend. If anyone sums up this place then it's that fella."
Millwall continue their Championship campaign next Saturday when they make the trip to Watford.