The senior academy hooker crossed for two tries in last week's loss to New Zealand.
Ollie McKenna and Dan Halkon join Roberts in the starting pack with Alex Bryden and Jackson Rennie on the bench.
Glasgow Hawks' duo Cameron Waugh and Harvey Preston also start for the Scots.
Scotland U20
15 Rory McHaffie (Edinburgh Rugby)
14 Daniel Kelly (Edinburgh Rugby)
13 Campbell Waugh (Glasgow Hawks)
12 Henry Kesterton (Edinburgh Rugby)
11 Nairn Moncrieff (Edinburgh Rugby)
10 Jake Dalziel (Merchiston Castle/Newcastle Red Bulls
9 Matthew Fick (Edinburgh Rugby)
1 Ollie McKenna (Glasgow Warriors)
2 Joe Roberts (Glasgow Warriors) CAPTAIN
3 Ollie Blyth-Lafferty (Edinburgh Rugby)
4 Christian Lindsay (Edinburgh Rugby)
5 Dan Halkon (Glasgow Warriors)
6 Sam Byrd (Edinburgh Rugby)
7 Jack Utterson (Edinburgh Rugby)
8 Harvey Preston (Glasgow Hawks)
Substitutes
16 Jamie McAughtrie (Ayr RFC)
17 Jamie Stewart (Edinburgh Rugby)
18 Jackson Rennie (Glasgow Warriors)
19 Finlay Mather (Grammar Tec)
20 Oliver Finlayson-Russell (University of St Andrews)
21 Asa Stewart Harris (Saracens)
22 Alex Bryden (Glasgow Warriors)
23 Ewan Caven (Gloucester Rugby/Nottingham University)