McGowan has swapped UAE Arabian Gulf League side Al-Sharjah for the Yorkshire side, who currently sit in fifth place in League One.
McGowan's move to the Bantams, on a free transfer, is subject to international clearance, but should give the defender game time and a chance to impress new national team boss Bert van Marwijk ahead of the 2018 FIFA World Cup.
The 28-year-old, who has 20 caps for Australia, started his professional career at Heart of Midlothian, before joining Shandong Luneng Taishan after loan spells at Ayr United and Partick Thistle.
He then left China to return to Scotland with Dundee United, before heading back to Asia with Henan Jianye and Guizhou Zhicheng.
McGowan's signing was one of four new faces for the Bantams in the space of two days, with Burton Albion duo Matthew Lund and Stephen Warnock's loan deals until the end of the season coming a day after the club landed striker Kai Brunker from SC Freiburg.
Stuart McCall's side host AFC Wimbledon on Sunday morning (AEDT).
