The midfielder maintained his fine form with both goals as his team came from 1-0 down to win 2-1 in Ljubliana.
Gylfi struck a fine free-kick to level the scores on 55 minutes before a clinical finish from 12 yards out to secure the points 12 minutes from time.
Interestingly, Gylfi's winner was set-up by two former Spurs players - Emil Hallfredsson and Eidur Gudjohnsen.
The victory means Iceland are joint-second in European qualifying Group E with Albania with three wins and two defeats in their five matches so far.
Switzerland top the group with a game in hand and remain unbeaten - Iceland travel to Switzerland in September.
The eight best runners-up from nine groups go into two-leg play-offs in European qualifying for the finals in Brazil in 2014.