Fly half Gareth Anscombe kicked Blues into a deserved early lead at the national stadium with three penalties.
However, tries either side of half-time from Dan Evans and Dan Biggar swung the game back in Ospreys favour.
Tom Grabham extended the lead before the dynamic Josh Navidi hit back for Blues with a superb solo try.
Ben John wrapped up the bonus point for Ospreys before Dan Fish scored a length of the field intercept try in the dying seconds.
A lively start saw Anscombe charge down a kick away from Biggar to spark early alarm bells ringing for Ospreys while Rhys Patchell’s neat kick in behind forced Dan Evans to dot the ball down and stop an early score.
The majority of the game was being played in the skies above the field in the opening minutes with both teams kicking for territory.
Rhys Webb failed to take Anscombe’s high up and under as Blues continued to dominate early possession. And when a penalty was secured it was fly half who slotted the first points.
A superb try saving tackle from Tom Isaacs denied Eli Walker before Ospreys nearly pressed the self-destruct button again as a poor pass allowed Tuculet to hack away and then Walker missed the ball under pressure from Garyn Smith.
A second penalty from Anscombe extended the lead after 12 frenetic minutes while Justin Tipuric and Sam Warburton came face-to-face in a ferocious tackle exchange.
Ospreys looked set to strike back as Grabham broke into space and Josh Matavesi showed neat handling to feed Dan Baker to crash over. However, after consultation with the TMO, the try was chalked off for a knock on.
Anscombe nudged over another penalty for a 9-0 lead before Navidi made a typically powerful burst from the restart and Amorosino tested Walker’s defence out wide with the Ospreys man up to the task.
Patchell then showed a clean pair of heels to cut through and possession found Isaacs only for his final pass to just fail to find the supporting Tuculet on his shoulder.
Ospreys had been quiet for long spells, but typically they exploded into life just after the half hour to score the game’s first try.
The elusive Biggar raced away down the middle of the field, Welsh prop Nicky Smith handed off two tacklers out wide and duly popped the pass to Evans to dart over to cut the lead to 9-7 at the interval.
Biggar missed an early second half penalty but made amends in stunning fashion moments later when he benefitted from a robust run from Alun Wyn Jones and showed his pace to race away and over the whitewash.
Ospreys threatened again as neat handling from Matavesi and Baker put them into space as Biggar started to run the game for Swansea side.
And it Grabham who scored a third Ospreys try after a slick backs move that blew open space out wide right for the wing to slide over.
Blues looked to hit back with Garyn Smith diving in the corner after neat hands down the line but a foot in touch saw the try ruled out.
However, moments later, out of nowhere, clean lineout ball was fed to Navidi who battered off tackles on the 22 and tore over unopposed to a huge ovation to get Blues back into the game and five points behind.
Biggar extended the lead with a penalty and any hopes of a late comeback from Blues were extinguished when an overlap sent John over in the far right corner.
Blues looked to mount a rearguard effort in the final ten minutes with Anscombe twice going for the corner to try and set up drives and Amorosino dancing past tacklers and close to the line.
And it was Fish who had the final word in injury time as, when Ospreys looked to fling a wide pass out, he shot out of the line, intercepted and raced the length of the field to score.
Timeline:
07m Anscombe p 3-0
12m Anscombe p 6-0
28m Anscombe p 9-0
37m Evans t Biggar c 9-7
45m Biggar t Biggar c 9-14
55m Grabham t Biggar c 9-21
58m Navidi t Davies c 16-21
60m Biggar p 16-24
68m John t Biggar c 16-31
80m Fish t Anscombe c 23-31
Cardiff Blues: 15 Rhys Patchell (Fish 57), 14 Lucas Amorosino, 13 Tom Isaacs, 12 Garyn Smith (G Davies 70), 11 Joaquin Tuculet, 10 Gareth Anscombe (Davies 57-66), 9 Lloyd Williams (L Jones 70); 1 Gethin Jenkins (Hobbs 26-33, 61), 2 Kristian Dacey (Rees 46), 3 Craig Mitchell (Andrews 69), 4 Chris Dicomidis (Cook 61), 5 Filo Paulo (Hoeata 46), 6 Josh Turnbull, 7 Sam Warburton, 8 Josh Navidi
Replacements: 16 Matthew Rees, 17 Sam Hobbs, 18 Scott Andrews, 19 Jarrad Hoeata, 20 Macauley Cook, 21 Lewis Jones, 22 Gareth Davies, 23 Dan Fish