Lively flanker Willie Faloon showed that his score last weekend against the Ospreys was not a once-off as he followed up with two tries in an impressive team performance at the Arms Park.
Although the home side recovered from an early deficit to edge in front midway through the second half, they were unable to hold off the enthusiastic visitors.
The only occasion Connacht had previously managed a win in the Welsh capital was in the pre-regional era, when current had coach Eric Elwood kicked them to a 6-3 success over Cardiff RFC back in 2001.
This is the first time since last April that the westerners have put together back-to-back league wins, and the result has moved them into eighth position above Benetton Treviso who host Munster on Sunday afternoon.
Connacht's achievement is all the more commendable given their list of absentees this week - Dan Parks, Robbie Henshaw, David McSharry, Tiernan O'Halloran, Frank Murphy, Mike McCarthy, Johnny O'Connor and George Naoupu.
Their chances of beating the Blues for only the third occasion in 20 matches took a hit before kick-off when Parks, who scored 347 points in 38 appearances for the Blues before crossing the Irish Sea last summer, was ruled out by a hamstring strain.
However, Elwood's fired-up side ran in two tries in a blistering first five minutes and the first of them came from South African Danie Poolman.
Fast handling among the backs saw captain Gavin Duffy join the line to send Poolman speeding in at the corner for his fifth try in nine league starts.
And before the Blues could gather themselves, debutant Brian Murphy's eye-catching run and offload put Faloon charging through some weak tackling to grab his second try in Connacht colours. Miah Nikora converted the flanker's effort for a 12-0 lead.
As the home team began to get a foothold in the Connacht half, Rhys Patchell landed a long range penalty to get them off the mark.
The young out-half was heavily involved, along with Irish number 8 Robin Copeland, in a move which saw winger Harry Robinson dive in at the left corner after 21 minutes. Patchell was off target with the conversion.
Nikora responded with a penalty when the Blues backs strayed offside but, despite some welcome adventure by both sides, there were no further scores before the interval.
The Blues piled on the early pressure in the second period, but had to settle for a penalty by Patchell after Connacht hooker Jason Harris-Wright, in an offside position, had impeded scrum half Lewis Jones.
The punishment was doubled when referee Dudley Phillips reached for his yellow card and Connacht, having defended with discipline and excellent organisation, were now coming under increasing pressure.
Patchell slotted over another penalty for a 15-14 scoreline, but it was soon cancelled out by a similar effort from Nikora and when an aggressive Blues scrum allowed Patchell a further opportunity at goal the teenager pulled it wide.
The Arms Park crowd's disappointment was shortlived, however, as lovely hands from debutant Liam Davies allowed Wexford man Copeland to gallop over just before the hour mark, putting the Blues ahead for the first time.
But the Welsh region's lead was not to last, with Faloon darting over from a scrum for his second try with a quarter of an hour left on the clock.
Patchell's fourth penalty cut the gap to a single point, but Connacht, sensing an upset, forced the Blues back into their own 22 with some talismanic turns from the experienced Duffy, John Muldoon and Michael Swift.
The new centre pairing of Eoin Griffin and Murphy also combined to very good effect, particularly as Cardiff looked to punch holes in midfield, and Nikora capped off a fine outing in the number 10 shirt with what turned out to be the clinching penalty.
The former New Zealand underage international was able to add another penalty from a difficult angle, following a Blues infringement, and Connacht stood firm in the face of a late onslaught from the hosts.
|Cardiff Blues Score Card|
|Connacht Rugby Score Card|