Two tries in each half saw Gearoid Prendergast's side, who won the delayed Munster Senior Cup final in August, get the better of a 'Hinch outfit that made it very tricky throughout.
Adam Craig's charges shaded the opening quarter, but a great piece of ingenuity from Young Munster out-half Evan Cusack helped to break the deadlock.
Cusack spotted a gap in behind the defence and a beautifully-crafted chip was inch perfect for winger Conor Hayes to touch down in the corner. Cusack then nailed a splendid touchline conversion for a 7-0 lead.
However, Ballynahinch were back on level terms seven minutes before the break. Scrum half Chris Gibson intercepted a wayward pass and ran in from 40 metres out, with his half-back partner Greg Hutley supplying the conversion.
With the game heading towards the half-time whistle, the Cookies struck again. The outstanding Patrick Campbell made a break on the left wing from his own 22 before passing inside to Shay McCarthy.
The young winger had Paddy Wright to beat and he did so with a sumptuous step off his left foot. McCarthy then had enough pace to beat Aaron Cairns' attempted ankle tap to score under the posts.
Again, the increasingly-influential Cusack popped over the resulting conversion to see the home side to a 14-7 half-time advantage.
Munsters made a quick start to the second half when Cusack's penalty put them in good position deep in 'Hinch territory. A patient build-up brought them close to the line and scrum half Adam Maher dived over for try number three.
Cusack was on target with the conversion and then a penalty on 53 minutes, giving Young Munster a commanding 24-7 lead in front of a vocal home crowd.
The bonus point was sewn up in the final stages when replacement hooker Aaron Hennessy crashed over after a powerful lineout maul.
That made it 22 points without reply and sealed an impressive win ahead of next week's trip to defending champions Cork Constitution.
YOUNG MUNSTER: Patrick Campbell; Conor Hayes, Harry Fleming, Jack Harrington, Shay McCarthy; Evan Cusack, Adam Maher; Conor Bartley, Mark O’Mara, Colm Skehan, Tom Goggin, Sean Rigney, Alan Kennedy (capt), John Foley, Bailey Faloon.
Replacements: Aaron Hennessy, David Begley, Fintan Coleman, Dan Walsh, Jack Lyons, Patrick Ryan.
BALLYNAHINCH: Paddy Wright; Ronan Patterson, Yasser Omar, Ryan Wilson, Aaron Cairns; Greg Hutley, Chris Gibson; Ben Cullen, Zack McCall (capt), Kyle McCall, James Simpson, John Donnan, Thomas Donnan, Oli Loughead, Callum Irvine.
Replacements: Tom Stewart, Peter Cooper, Bradley Luney, Diego Vidal Souza, Ruairi Meharg, Jack Milligan.