The Scarlets lost Wales’ Liam Williams to a red card for colliding with his international team-mate Shane Lewis-Hughes at a ruck.
But in their fly-half Evans, the Blues had the game’s best player.
Evans made two superb breaks – one created a try for Willis Halaholo – and kicked a conversion and four penalties.
“It was certainly entertaining, speaking from a Blues point of view the intent was a lot better,” said the 24-year-old playmaker.
“We went out there to express ourselves and we did that with a lot of confidence but also in a controlled manner as well.
“We knew when to manage the game but also show some of the talent we have which we haven’t always done this year.”
Further Blues tries came from Rey Lee-Lo and Tomos Williams with Evans also playing a key role in both of those scores.
Scarlets tries came from Jonathan Davies and Sione Kalamafoni.
“We certainly wanted to put our stamp on the game and play with intent and we did that in the first half,” said Blues captain Cory Hill.
“The red card at the end of the half probably killed the game which was disappointing, but we wanted to come out in the second half and we struggled to do that due to ill-discipline.”
Reflecting on the trio of festive derbies, Hill continued: “We got the win down at the Dragons. The weather didn’t let us play the game we wanted to, but we won ugly and got the four points.
“It was disappointing to come here to the Cardiff City Stadium and perform like we did against the Ospreys. We had to bounce back and we certainly did that.”
