A 24-year-old cleaner who was sacked from Myer after blowing the whistle on widespread exploitation of cleaners has been reinstated after winning huge community support.

Colombian-born Rafael Colobon told ABC's 7:30 program dozens of cleaners were being ripped off through subcontracting and sham contracts.

He said workers were being paid below the award rate, denied penalty rates and superannuation, and working without Work Cover insurance.

Although Mr Colobon's identity was not revealed in his interview to 7.30 because he feared reprisals, his contractor, a labour hire firm called INCI Corp, which works for Myer's cleaning contractor Spotless Group, sacked him.

Mr Colobon launched Federal Court action seeking to be immediately reinstated, arguing he was unlawfully sacked for speaking out.

On Friday the court ruled in his favour and Mr Colobon will return to work on Monday pending his full case against his employer in December.

"I am so happy. I wasn't just fighting to get my job back. I was fighting for everyone's right to speak out when employers do the wrong thing, like putting us on sham contracts and underpaying us," Mr Colobon said.

"This is a huge place, Myer, I didn't understand why they were doing this, that's why I spoke out, not only for me but for everyone else."

He urges others who feel mistreated to come forward.

"Don't be afraid, if you're sure about what you're doing and think it's right, you shouldn't be afraid of anything, speak out."

Mr Colobon was working in a Myer store for about three and a half months and was underpaid approximately $7,000.

After the news of Mr Colobon's sacking, almost 4,000 people signed an online petition to Myer and supporters also took to social media with the hashtag #ReinstateRaf.

"It's pretty amazing, you know I was everywhere on Facebook," Mr Colobon said.

'Year of rip offs and exploitation in Australian workplaces'

Jess Walsh from the cleaners' union, United Voice, said the Federal Court finding was a victory for any worker being exploited.

Ms Walsh said the union was investigating dozens of similar cases at Myer stores across Victoria.

"During this process we've sought to get in touch with both Myer and Spotless, who's the principal cleaning contractor at Myer, and neither of them has been willing to work with us on this," Ms Walsh said.

Ms Walsh said 2015 has been the "year of rip offs and exploitation in Australian workplaces" including 7-11, Pizza Hut and Australia Post.

"What is in common with all of this wage theft and exploitation is that these big companies are hiding the rip offs behind layers of subbies and sham contracts that are in place in their workplaces and no one is taking responsibility for it.

"People rely on these insecure jobs to get by and they're scared to speak out. Right now, no one will take responsibility for what's happening to them. Everyone's looking the other way.

"The big companies are saying 'it's not our problem we don't actually employ these people', but these are real people with real jobs who need their income to get by and it's important that big companies like Myer in this case stand up and say we don't support these rip offs and we're going to stand up and do something about it."

ABC's PM has been unable to contact the subcontractor INCI.

The night of the 7:30 story, INCI moved its contractors off a contentious ABN system, and appointed them as employees, bringing them up to award rates.

Last week the ABC revealed Myer rejected an offer from the Fair Work Ombudsman to enter into a voluntary compliance deed to ensure its workers are paid properly.