A disappointing opening defeat to Sale Sharks saw the Blues drop put of the cup but they went all the way – winning five from six in total during the series.
They faced a strong Harlequins outfit, one of the favourites to win the tournament, but showed an abundance of grit and determination to take the spoils.
Richard Hodges and Paul John’s side trailed 12-0 early in the first-half and were one-point adrift in the closing stages.
But they refused to throw in the towel and Aron Wyn Evans powered over at the death to snatch victory from the jaws of defeat.
Wales’ Capital Region made a fine start to their quarter-final, which kicked-off the action at a sun-kissed Ricoh Arena, with Jenkins and Lewis scoring quick-fire tries.
Following an attritional opening period the Wales 7s star powered over from a quick-tap and a minute later Lewis showed his devastating pace from the back of a scrum.
The Blues led 10-0 at the break but Sale Sharks hit-back straight from the restart thanks to Tom Curry,
They took the lead when James Mitchall converted Ben Curry’s effort but Cardiff Blues fought back.
Hodges and John’s side responded in perfect fashion with some good inter-play putting Jenkins on the front foot and he broke a tackle in midfield to race clear.
Ethan Davies converted the try to restore a 17-12 lead but the helter-skelter nature of the encounter continued and late tries from Paolo Odogwu and Curtis Langdon sealed a Sale Sharks win.
Wales’ Capital Region faced Northampton Saints, who were thumped by Exeter Chiefs in match two, in the plate semi-final and eased past the Franklin’s Gardens outfit.
It took just 40 seconds to knock the scoreboard into action with Declan Williams breaking and selling a dummy to canter home with Ethan Davies converting.
Saints responded through Joe Green but some fine work from Jenkins opened up the defence and after cutting back inside he timed a scoring pass to Davies to perfection.
Beale was next to cross, handing the Blues a 19-4 half-time lead and the tries continued to come following the break.
Thomas, Lewis and Joe Tomlinson all crossed before the Saints claimed a consolation try but it was too little, too late as the Blues inflicted a 40-10 defeat.
Quins were the opponents in the second-tier final and the Blues got off to the worst possible start as tries from Oscar Hirskyj-Douglas and Dino Lamb-Cona tries gave the London club a 12-0 lead.
Cardiff Blues hit back with a converted try from Ethan Davies and a stunning team effort sent James Beale over the whitewash, with Davies converting to make it 14-12.
Quick-fire tries from giant wing Jonas Mikalcius put Quins in the ascendant and it looked as though injuries had taken their toll on Wales’ Capital Region.
But they fought tooth and nail and with 40 seconds left on the clock they created a match-winning try.
They won the restart and a break down the middle from Declan Williams laid the foundations.
Lewis maintained the momentum before Wyn Evans exploded out of a double tackle to stretch over and seal a 28-22 triumph.
Cardiff Blues 17 (Jenkins 2, Lewis)
Sale Sharks 24 (T Curry, B Curry, Odogwu, Langdon)
Exeter Chiefs 38 (Simmonds, Mason, Jess 3, Landry)
Northampton Saints 12 (Emery, Dix)
Wasps 24 (Wade, Bassett 2, Howe)
Harlequins 19 (Hirskyj-Douglas, Cowell, Mikalcius)
Newcastle Falcons 17 (Catterick, Radwan, Ffitch)
Ospreys 28 (Williams 2, O’Flaherty, Phillips)
Cardiff Blues 40 (Jenkins, Davies, Beale, Thomas, Lewis, Tomlinson)
Northampton Saints 10 (Lozias, Kingham)
Harlequins 45 (Mikalcius, Ibitoye 3, Waters 2, Smith)
Newcastle Falcons 21 (Marshall, Radwan 2)
Sale Sharks 21 (T Curry, Odogwu, Scott)
Exeter Chiefs 26 (Simmonds 2, Hendrickson, Cully)
Wasps 24 (Thompson, Halai, Howe, Wade)
Ospreys 14 (O’Flaherty 2)
Saracens 29 (Mackinder 2, Okemba, Vistisen 2)
Bristol Rugby 7 (Vaughan Fowler)
Cardiff Blues 28 (Davies, Beale 2, Jones)
Harlequins 22 (Hirskyj-Douglas, Lamb-Cona, Mikalcius 2)
Exeter Chiefs 28 (Bodilly 3, Simmonds)
Wasps 31 (Thompson, Halai, Howe, Wade, Cruse)