Giske has been on sick leave from parliament since reports over his conduct were made in December.
Speaker Olemic Thommesen confirmed that Giske was available to attend the parliamentary session on Wednesday.
"Representative Giske, who had been temporarily absented, has resumed his seat," Thommesen said as he opened the meeting at the Stortinget parliament in Oslo.
Giske was did not appear to be physically present at Wednesday's meeting, according to reports by several media including NRK.
News agency NTB reported that the former deputy leader had not been entered into the parliament's registration system, while newspaper Aftenposten writes that it received confirmation from parliament's administration that Giske had been reported healthy following his sick leave.
The former leader's apparent absence from the chamber could be down to an exchange agreement (utbytting in Norwegian) in which political parties arrange for members of opposing views to remain absent, thereby preserving relative voting strength, NRK reports.
Giske is scheduled to make his first official party appearance since the scandal on Saturday, when he will open a local party meeting in Sør-Trøndelag, VG reports.
The Labour party has since December 20th received over 20 complaints relating to inappropriate sexual behaviour, of which a number are against Giske.
In a letter to the party's central committee on February 1st, Giske contested three of the complaints made against him and also criticised the process of the party investigation into the reports. He also apologised for his conduct in two other cases, NRK reports.
Party leader Jonas Gahr Støre said that Giske's letter had not given a full version of events.