Debutant Dan Kelly made an instant impact, scoring a brilliant solo try inside two minutes, while Jake Dalziel added a try and three conversions as Scotland took a 19-14 lead into half-time after further scores from Rory McHaffie and Kelly's early opener.
Italy fought back strongly after the break, briefly moving ahead at 29-24, but Scotland responded superbly. Nairn Moncrieff crossed for his second-half try before McHaffie grabbed his second and Henry Kesterton sealed the win with a late score, converted brilliantly by Dalziel.
Italy claimed a losing bonus point with a late penalty, but Scotland's clinical finishing and resilience ensured a winning start ahead of Thursday's clash with New Zealand.
Scotland U20
15 Rory McHaffie (Edinburgh Rugby)
14 Dan Kelly (Watsonian FC)
13 Henry Kesterton (Edinburgh Rugby)
12 Ross Wolfenden (Edinburgh Rugby) - Co-Captain
11 Nairn Moncrieff (Edinburgh Rugby)
10 Jake Dalziel (Merchiston Castle School/Melrose RFC)
9 Matthew Fick (Edinburgh Rugby)
1 Jamie Stewart (Edinburgh Rugby)
2 Joe Roberts (Glasgow Warriors) - Co-Captain
3 Ollie Blyth-Lafferty (Edinburgh Rugby)
4 Alfie Blackett (Cardiff Metropolitan University)
5 Dan Halkon (Glasgow Warriors)
6 Christian Lindsay (Edinburgh Rugby)
7 Jack Utterson (Edinburgh Rugby)
8 Harry Jackaman (Watsonian FC)
Substitutes
16 Jamie McAughtrie (Ayr RFC)
17 Will Pearce (Bristol Bears/Cardiff Metropolitan University)
18 Jackson Rennie (Glasgow Warriors)
19 Sam Byrd (Edinburgh Rugby)
20 Harvey Preston (Glasgow Hawks)
21 Oliver Finlayson-Russell (University of St Andrews)
22 Asa Stewart-Harris (Saracens)
23 Alex Bryden (Glasgow Warriors)