Cardiff dominated possession, but were undone far too easily by Neil Lennon’s clinical side, who now have a 13-point buffer on those in the relegation zone.
An early Emile Heskey chance sparked a spell of Bluebirds dominance that saw Josh Vela booked for a late swipe at Peter Whittingham.
The City playmaker soon had a chance of his own after sparking a move that saw Craig Noone find him on the edge of the box, but his low drive flew just wide.
Noone cut in from his left flank and fired just wide before the Bluebirds had their best chance to open the scoring.
A Whittingham corner landed at the feet of striker Eoin Doyle, who spun and shot, but he was denied by Barry Bannan on the Bolton line amid cries of handball.
Just when the Trotters seemed to be pegged back, they had a chance of their own when Dorian Dervite rose highest to meet Bannan’s corner, but Alex Revell was on hand to head away the goalbound effort.
Joe Mason replaced the injured Revell before Gudjohnsen slipped in Davies who curled a clear-cut chance just wide.
And they were almost made to pay after Gudjohnsen fouled his Iceland team-mate Aaron Gunnarson on the edge of the box, but Whittingham bent the free-kick inches past the post.
The Cardiff City Stadium was shocked into silence in the 55th minute when Gudjohnsen put the below-par Wanderers ahead.
Heskey took the sting out of a strong pass with his chest to set up the former Chelsea and Barcelona man inside the 18-yard box, and he lashed a left-footed strike into the top corner.
And it was 2-0 less than five minutes later, with Heskey providing the scoring pass once more.
His assist found Davies charging down the left wing, and the striker powered into the box and cracked a low shot through the legs of Marshall and into the bottom corner.
Cardiff fans streamed out of the stands when Davies put the contest well and truly to bed in the 73rd minute.
He bagged his brace by once again darting off his left flank and past Fabio before he bent the ball around the Marshall into the same corner he had scored in 14 minutes earlier.
And Davies could have got a hat-trick soon after when he broke clear of the Cardiff defence, but Marshall denied him with his legs.