Cardiff give Ulster the Blues
Evans scored the first of the Blues’ four tries, Blaine Scully and Kristian Dacey also going over before Dillon Lewis' last-gasp effort secured the 35-17 bonus point win as they closed the gap to the Cheetahs, third in Conference A, to only five points.
Meanwhile, Ulster – who are fourth in Conference B – had John Cooney kick four penalties before a late Dave Shanahan consolation.
The Irish province are now 13 points behind Edinburgh in third and looking over their shoulder at Benetton just a point behind them in fifth.
The Blues meanwhile have won five in a row for the first time since the 2009/10 season and signed off in their final regular season home game in fine style before a crucial trip to Bloemfontein next up.
The visitors – with Iain Henderson and Jacob Stockdale both straight back into provincial action – have only lost one of their last six meetings with the Blues.
But they struggled from the outset against the in-form hosts, Evans ghosting over under the posts for the first try inside five minutes and adding the extras himself for a 7-0 lead.
Cooney replied with a penalty but the Blues attack was clicking and Matthew Morgan and Tomos Williams combined to release Scully down the right and the American stepped back inside to go over for their second.
Already chasing the game, Ulster then turned down two kickable penalties to go to the corner but the Blues held firm.
And things got worse for the visitors when Wiehan Herbst saw yellow for a swinging arm at a clearout before the half-hour mark and the Blues thought they had a third when Tomos Williams went over.
But the try was ruled out for a forward pass and before the interval Cooney slotted a second penalty to give Ulster hope.
However, the Irish province could not get the ball off the field before half-time and the Blues won a penalty that Evans slotted to make it 17-6 at the break.
The Irish province needed the first score of the second period to get them back in the game and it was the right foot of Cooney that again provided it with a long-range penalty to trim the lead to eight points.
And another soon after from the unerring boot of Cooney made it 17-12 as the hour mark came and went.
But after 16 phases in the Ulster half, that man Evans released Dacey for their third try to put the game to bed.
Evans' right boot extended the lead further before the Blues then turned their attention to a bonus point.
And while Ulster replacement Shanahan went over for the visitors, there was still time for the Blues to claim what could be a vital fourth when Evans fed replacement prop Lewis to crash over.
For Cardiff Blues:
Tries: Evans, Scully, Dacey, Lewis
Cons: Evans 3
Pens: Evans 3
Pens: Cooney 4
Yellow card: Wiehan Herbst (Ulster, 28 – foul play, swinging arm)
Cardiff Blues: 15 Matthew Morgan, 14 Blaine Scully, 13 Rey Lee-Lo, 12 Willis Halaholo, 11 Owen Lane, 10 Jarrod Evans, 9 Tomos Williams, 8 Nick Williams, 7 Ellis Jenkins, 6 Josh Turnbull, 5 Seb Davies, 4 George Earle, 3 Scott Andrews, 2 Matthew Rees, 1 Gethin Jenkins (captain).
Replacements: 16 Kristian Dacey, 17 Rhys Gill, 18 Dillon Lewis, 19 Ben Murphy, 20 Macauley Cook, 21 Lloyd Williams, 22 Steve Shingler, 23 Garyn Smith.
Ulster: 15 Charles Piutau, 14 Craig Gilroy, 13 Luke Marshall, 12 Stuart McCloskey, 11 Jacob Stockdale, 10 Johnny McPhillips, 9 John Cooney, 8 Nick Timoney, 7 Clive Ross, 6 Iain Henderson, 5 Kieran Treadwell, 4 Alan O'Connor (captain), 3 Wiehahn Herbst, 2 Rob Herring, 1 Andrew Warwick.
Replacements: 16 John Andrew, 17 Callum Black, 18 Ross Kane, 19 Matthew Dalton, 20 Matthew Rea, 21 Dave Shanahan, 22 Peter Nelson, 23 Louis Ludik.
Referee: Mike Adamson (Scotland)
Assistant Referees: Sam Grove-White, Dunx McClement (Scotland)
TMO: Andrew McMenemy (Scotland)