Canada, in their first Churchill Cup final, hit back as Matt Evans and Chauncey O'Toole touched down, but two more Myler penalties ensured the Saxons led 23-13 at half-time.
A converted try from Jon Clarke early in the second period finished the game as a contest, before Luke Narraway got on the scoresheet with 20 minutes to play.
Head coach Stuart Lancaster said: "It's a fantastic achievement. Three weeks ago we met in a Heathrow hotel with disappointed players not making the senior tour and young players who came in straight from the Premiership and collectively to put all that together and form a team is great, I'm really proud.
"We want to make sure these players have enough room to grow and develop so when they make the step to the senior stage they're ready."
Meanwhile, Worcester hooker Aleki Lutui tasted narrow defeat again in the ANZ Pacific Nations Cup as Tonga were defeated 41-38 by Fiji after a stunning second half comeback.
Despite trailing 31-10 at half time, Fiji ran out eventual 41-38 victors in Apia and are now just one win away from a first ever PNC title.
Having beaten Japan 22-8 last week, Fiji will now play Samoa on 26 June, with a win ensuring their name will be etched on the PNC trophy for the first time ever, whilst the result was heartbreak for Tonga as the side again lost narrowly after losing 24-23 to Samoa in the opening round.
Tonga captain Lutui said: "We are very disappointed. The same thing from last week happened again. We improved at the set pieces and scrums but our defence was poor in the second half. Fiji came out very strong in the second half and made us pay for the lack luster performance in the second half."