Bluebirds boss Malky Mackay was named manager of the month for November with his side having won five of their last six matches as well as securing a Carling Cup semi-final against Crystal Palace.
But they could not find a way past stubborn Millwall and had to settle for a point to stretch their unbeaten run to nine games.
In fact, the lowly Lions had the better chances to secure the victory with James Henry hitting the crossbar in the first half and Darius Henderson heading over late in the second.
However, the visitors remain in third and on the shoulder of the top two, who both dropped points on Saturday afternoon.
Clearly brimming with confidence, City went straight on the attack and Peter Whittingham combined with Joe Ralls before firing in a 20-yard drive which Lions keeper Steve Mildenhall did well to keep out.
Ralls, City's 18-year-old midfielder making his full league debut, looked assured on the ball and was not afraid to have a shot either, firing over in the 20th minute.
The youngster then teed up Kenny Miller, who jinked forward into a shooting position but lifted his effort too high.
But Millwall came agonisingly close to opening the scoring with their first real attack
Lone striker Jay Simpson won possession and played the ball in behind the defence for flying winger Liam Feeney.
His low cross found James Henry in front of goal but the midfielder's shot crashed back off the woodwork.
Another swift counter-attack saw Liam Trotter charge forward and find Simpson, who curled his effort the wrong side of the post.
It was Simpson's last action of the match as he was replaced at half-time by top scorer Henderson, a surprise omission from the starting line-up with boss Kenny Jackett opting for an extra man in midfield.
Four minutes into the second half Cardiff sub Joe Mason got a sight of goal but his shot was comfortably dealt with by Mildenhall.
Hamer Bouazza came close to nicking it for Millwall with 15 minutes left when he fizzed the ball across goal and inches past the post.
At the other end Miller brought a save from Mildenhall with a glancing header and Rudy Gestede blazed a late chance over.
Henderson had a superb chance to win it for the Lions at the death but his downward header bounced back off over the crossbar.
Source: DSG