Millwall took the lead through Matt Smith's first-half header. Ben Thompson should have made it 2-0 but he missed a free header from six yards out.
Kieffer Moore equalised for Cardiff on 79 minutes.
Jon Dadi-Bodvarsson then had a golden opportunity to win it for the hosts after being played through by Ryan Woods but his effort was off target.
On the performance
It was a game of few chances particularly in the first half, Smith's goal the only real opportunity that fell either side's way.
“It wasn’t as good a performance as I’d have liked but we worked incredibly hard. Just before their goal, we had an opportunity with Thommo [Ben Thompson]. It’s a chance we should take, it’s a really easy chance. To go 2-0 up at that point would have killed the game off."
On the equaliser
“Cardiff then put us under pressure but we actually looked at our most comfortable just before the goal. We looked like we’d see the game out. Then we make a poor mistake. Scotty [Malone] tries to play a cross-field pass, I don’t think he has a shout and it then opens the game up. We’re still two-v-one defensively against Moore and we should deal with it. Coops [Jake Cooper] needs to react a little bit quicker. It gets a deflection and sends Bart [Bialkowski] slightly the wrong way."
“That gave Cardiff a lift for five minutes, they had us on the rack and looked more likely to score the next one. We had to make a couple of good blocks or saves."
On Ben Thompson
Ben Thomspon was making just his third league start of the season and missed the chance that could have sealed all three points when the scoreline was at 1-0.
"It’s not necessarily a criticism of Thommo, missing a chance. He’s had another one when he’s turned and whipped it just wide.
“I think that’s his position as a 10. We’ve been playing 5-2-3 but we’ve not managed to win enough games at home, we’ve drawn a lot.
“We just thought we’d take the opportunity today to flip to 4-2-3-1, to give us another body further forward. I think he was bright, Thommo, he hasn’t played much so after 65, 70 minutes we knew he’d have to come off.