There were no second-half tries for either side, however Biggar sealed the win for Wales with a late drop-goal after Russell received a 68th-minute yellow card for a deliberate knock-on.
Scotland were unable to fight back in the final stages of the match as Wales’ defence stood firm and guided them to victory.
Wales: L. Williams; Cuthbert, Watkin, Tompkins (J Davies, 69), Rees-Zammit; Biggar (capt; Sheedy, 79), T. Williams; W. Jones (G Thomas, 65), Elias (Lake, 65), Francis (Lewis, 59), Rowlands (S Davies, 75), Beard, Basham, Morgan, Moriarty (Wainwright, 57).
Replacements: Lake, G. Thomas, Lewis, S. Davies, Wainwright, G. Davies, Sheedy, J. Davies
Scotland: Hogg (capt); Graham, Harris, Tuipulotu (Kinghorn 72), Van der Merwe (Redpath, 79); Russell, Price (White, 62); Schoeman (Sutherland, 44-63), McInally (Turner, 44), Nel (Z. Fagerson, 44), Gray (Darge, 62), Gilchrist, Skinner, Watson, M. Fagerson (Bradbury, 31)
Replacements: Turner, Sutherland, Z. Fagerson, Bradbury, Darge, White, Kinghorn, Redpath