Neither player looked comfortable on serve, combining for 21 double faults and 15 service breaks at the indoor tournament.
Tauson had six aces and did not face a break point, also breaking Giorgi's serve five times in a dominant display.
The 139th-ranked Tauson, a former Australian Open junior champion, knocked out top-seeded Ekaterina Alexandrova in the first round.
She and Badosa are both looking to win their first WTA titles.
Second-seeded Fiona Ferro joined them in the last four in her bid for a third career title.
Ferro rallied to beat unseeded 19-year-old Clara Burel 2-6, 6-1, 6-3 in an all-French match where they dropped serve 12 times between them.
Golubic, a qualifier ranked 130th, is seeking her second career title.