The visitors, although struggling at the line-out, carried the greater firepower and did just about enough to complete a league double over their big rivals despite trailing for much of the game.
Ospreys coach Sean Holley admitted it was pleasing to see his side leapfrog Munster, who play Ulster on Saturday, at the summit.
“The league table is a satisfying sight but there is still a long way to go, but we’ve got to be confident because we are in a good position,” he said.
“The intensity was awesome; it gives me goose bumps reflecting (on it) and both teams know they’ve been in a huge game.”
Blues full-back Ben Blair landed the first after just two minutes, Ospreys responding through fly-half Dan Biggar, and both players missed further kicks before Blair restored his side’s lead.
Young Biggar played a key role when the Ospreys finally crossed the line just after the half-hour. His agility and sleight of hand kept the ball alive before Tommy Bowe fed Lee Byrne and the Wales number 15, in a rare outing on the wing, stepped inside flanker Maama Molitika to touch down.
The Blues’ own prodigy, 20-year-old Leigh Halfpenny — on for the injured Blair — raced through the visitors’ defence on a mazy 50-yard gallop but lost his footing just short of the try line.
A drop goal by Nicky Robinson ensured his good work did not go totally unrewarded, and gave the home side a narrow half-time lead.
The Ospreys threw down the gauntlet by bringing on Wales fly-half James Hook to replace Biggar.
Cardiff scored next, however, after a remarkable 60-yard break by Tom James had been ended illegally by Byrne, who received a yellow card while Robinson slotted the penalty.
A long-range kick by Hook kept Ospreys in touch and it needed two despairing tackles by Halfpenny to save the day as the visitors went in search for a winning score.
Their sustained pressure was rewarded with barely five minutes left, a superb long pass from Hook finding Tiatia on the left to dive over.
Despite their last-ditch efforts, the Blues were unable to respond as the visitors underlined their status as the best team in Wales.
Cardiff Blues scorers: Blair 2 pens; N. Robinson pen, drp gl.
Ospreys scorers: Byrne, Tiatia try each; Hook, Biggar pen each.
CARDIFF BLUES: Blair, Mustoe, Shanklin, G. Thomas, James, N. Robinson, Spice, Jenkins, G. Williams, Filise, D. Jones, Tito, Molitika, M. Williams, A. Powell.
Replacements: Halfpenny for Blair (20), Allinson for Spice (57), Morgan for Tito (57).
OSPREYS: Henson, Bowe, Parker, A. Bishop, Byrne, Biggar, M. Phillips, James, Hibbard, A. Jones, Gough, Wyn-Jones, R. Jones, Holah, Tiatia.
Replacements: Hook for Biggar (46), Nutbrown for M. Phillips (60), Thomas for Tiatia (76).
Referee: N Owens (Wales).