Wing Ethan Clayden opened the scoring after three minutes – converted by Will Reed – before Blues hit back with a penalty from Josh Phillips and try from Aneuran James giving the hosts the lead.
But second half scores from scrum half Dylan Davies, full back Jake Morgan and hooker Brodie Coghlan ensured the Dragons claimed a winning start to the season.
Timeline:
03m Clayden t Reed c 0-7
16m Phillips p 3-7
21m James t 8-7
37m Davies t Reed c 8-14
47m Cabango t Roberts c 15-14
51m Morgan t Reed c 15-21
64m Coghlan t Reed c 15-28
Dragons: 15 Jake Morgan, 14 Lewis Bates (Paynter 65), 13 Ollie Stansfield, 12 Ollie Lewis, 11 Ethan Clayden (McDonnagh 41), 10 Will Reed, 9 Dylan Davies; 1 Henry Hibbs, 2 Brodie Coghlan, 3 Owen Peddle, 4 Joe Peard (Oliver 58), 5 Ben Carter, 6 Benji Hoppe, 7 Oli Howard, 8 Ben Torjeson (Jefferies 41)
Replacements: 16 Jack Wakeley, 17 Aaron Dowse, 18 Clay Gibbons, 19 Callum Oliver, 20 Matthew Jefferies, 21 Joe Christofferson, 22 Jonny Paynter, 23 Carrick McDonnagh
Meanwhile, Dragons Under-16s Red (formerly known as North) lost 24-10 to Cardiff Blues Under-16s South at Ystrad Mynach. Dragons Under-16s Black (formerly known as South) lost out 26-5 at St Clears against Scarlets Under-16s West.