Galvin was touted as a future fashion-design star when he established clothing label Descendant Denim in 2009.
The brand later became Fistful of Bird due to copyright issues, receiving rave reviews from industry insiders.
One website described Galvin's work as "a new take on an old classic that boasts innovative cuts, seasonal washes and an uncompromising level of quality".
But three years later, the company folded.
Judge Heemi Taumaunu detailed the events of January 18 when the defendant had walked down Queen St with a cellphone strategically positioned in his bag.
"The cellphone was placed in a way video footage could be taken without people realising," the judge said.
The camera was positioned to see up women's skirts and Galvin later went into a clothing shop with the secret device.
He placed the bag by the bottom of a changing-room door, enabling the phone to capture footage of the woman inside who got undressed as she tried on garments.
Galvin was quick to take ownership of his actions and said he did not want to make excuses.
"What I did was completely unacceptable. It's not something I've ever done before in my life but it was at the tail end of what I see now as a very painful depressive breakdown," he said. "In a sense it's served, in a strange way, as a way out of that."
The defendant was already undergoing regular counselling to address historical causes of the offending and Judge Taumaunu sentenced him to 12 months of intensive supervision to continue the therapy.
Galvin, who now runs a furniture importation business, was also ordered to complete 100 hours of community work.
The judge highlighted Galvin's previously unblemished criminal record and also the many positive references provided to the court by his lawyer Marie Dyhrberg, QC, which he said proved the actions were "completely out of character".
Anti-sexual violence group Stop Demand founder Denise Ritchie disagreed.
"These types of crimes are not spontaneous or random. They are premeditated, planned and carefully executed," she said.
"They reflect a mindset that is very much a part of a person's character, albeit a secretive part of that character."
Ms Ritchie said given the growing number of hand-held electronic devices, the reduction in device size and improvements in resolution, the courts needed to crack down on offenders.
The sentence was "disappointing", she said, but she was pleased there was no application for name suppression.