The commission found the company’s private security operations were “outside the scope of what would be reasonable”.
It also found the company’s behaviour “undermines collective bargaining and freedom of association”.
Oaky North employees had complained that Glencore’s private security guards were monitoring them and their families at their homes and in Tieri.
One on occasion, a worker reported that a private security guard had filmed them using body cameras while they were at the local pub.
Evidence before the commission showed Glencore’s security company was briefed to monitor and record specific activities by union members.
The commissioner also ordered Glencore to withdraw a direction to staff regarding the wearing of union clothing at the mine, and to drop disciplinary action against workers.
Immediately following the decision, Glencore issued a further lockout of workers, taking the number of days locked out to 117.
Queensland Construction Forestry Mining and Energy Union district president Stephen Smyth said no employee in Australia should be subject to this level of control through private company policies.
“We are pleased with this fair decision from the Fair Work Commission,” he said.
“We are also committed to continuing to getting a fair and reasonable agreement that will benefit the members, their families and the community of Tieri.”
A Glencore spokesman said: “We are disappointed by the decision of the Fair Work Commission and are reviewing the ruling as we continue to negotiate a new enterprise agreement to position Oaky North for a successful future.
“Oaky North employees will vote this week on a new enterprise agreement offer.”