Centre Jamie Robinson grabbed two tries and brother Nicky contributed 12 points with the boot. The Blues got off the mark with two Nicky Robinson penalties, but flanker Andy Powell was injured when charging down a kick and was replaced by Robin Sowden-Taylor, but the Borders backrow was also disrupted when Kelly Brown was yellow-carded for slowing down ball.
The Scots survived their stint with 14 men, but were streched by gallop down the left touchline by Jonah Lomu, the giant New Zealander looking more like his old self than in previous outings for the Blues. However, it was American Kort Schubert who played a key role in the game's first try, collecting from scrum-half Mark Phillips to send Jamie Robinson speeding over for a touchdown which brother Nicky converted.
The Reivers began throwing the ball wide themselves and were rewarded before the interval when swift passing from right to left allowed centre Ben MacDougall to wrong-foot Chris Czekaj and cross for an unconverted try, but the Scots left a massive gap in midfield in the opening minute of the second half for Jamie Robinson to stroll under the posts and make it simple for his younger brother.
Reivers centre Calum MacRae, who had missed a couple of early kicks, found his range to keep his team in touch, but the Blues were not to be denied, a driving maul gaining 30 yards before Australian Marc Stcherbina sliced through and once again provided an easy conversion for Robinson.
MacRae pulled back another three points, but the Blues secured their bonus point when replacement Rhys Thomas went over from a driving lineout. Replacement fly-half Nick Macleod grabbed an opportunist try, converting it himself, and added the extras when Mark Lewis ended the scoring.
The celebrations were muted, however, as Lomu, hurt in the build-up, had to be helped off with a leg injury. The win means the Blues have now beaten all three Scottish regions in consecutive weeks.
Tries: Robinson J. 2, Stcherbina, Thomas, MacLeod, Lewis
Cons: Robinson N. 3, Macleod 2
Pens: Robinson N. 2
Pens: MacRae 2
Cardiff Blues: 15 Rhys Williams (c), 14 Jonah Lomu, 13 Jamie Robinson, 12 Marc Stcherbina, 11 Chris Czekaj, 10 Nick Robinson, 9 Mike Phillips, 8 Andy Powell, 7 Martyn Williams, 6 Kort Schubert, 5 Rob Sidoli, 4 Deiniol Jones, 3 Gethin Jenkins, 2 Duane Goodfield, 1 John Yapp
Replacements: 16 Martin Jones, 17 Rhys Thomas, 18 Chris Dicomidis, 19 Robin Sowden-Taylor, 20 Ryan Powell, 21 Nick Macleod, 22 Craig Morgan
Border Reivers: 15 Stuart Moffat, 14 Simon Danielli, 13 Ben MacDougall, 12 Calum MacRae, 11 Nikki Walker, 10 Gregor Townsend, 9 Brendan McKerchar, 8 Kelly Brown, 7 Scott Gray, 6 John Dalziel, 5 Opeta Palepoi, 4 Scott MacLeod, 3 Bruce Douglas (c), 2 Steve Scott, 1 Tom McGee
Replacements: 16 Will Kay, 17 Paul Thomson, 18 Colin Stewart, 19 Semo Sititi, 20 Johnny Weston, 21 Andy Miller, 22 James King
Referee: George Clancey (Ireland)
Touch Judges: DR Davies, Lynn Davies