The group, known as Iffley Open House, had previously occupied a former car showroom on Iffley Road, owned by Wadham College, on New Year's Eve.
They were asked to leave and then moved into the disused Osney Mill site in February.
The university said the former power station was unsafe won a  court order to evict the group.
Creative Solutions
It added that the building was due to be redeveloped by the Said Business School.
Some of the squatters said they were offered sleeping space at a local church, but most will now be back on the streets, the group said.
Volunteer Miranda Shaw said: "One good thing is that it has created enough of a stir that there are big conversations happening.
"We will be coming together in the coming weeks to meet churches, councils, the university, service providers and police.  There is the intention to find creative solutions."
Oxford University has always maintained that it is sympathetic to plight of the homeless and has been working towards resolving the situation.

Lucien PÃ©rot, 69, who had been drinking, choked on a 44g (1.5oz) beef rib he could not chew, reportedly because he had several teeth missing.
Olivier Boudin, 38, who had a pre-existing genetic heart condition, had a heart attack seeing his friend die.
There had been intense speculation over what had happened after their bodies were discovered last Thursday.
The men had been sharing a meal in Perot's garden in Authon-du-Perche, south-west of Paris, and drinking heavily. PÃ©rot was found to have 2.4g/l of alcohol in his blood.
One was found sitting on a chair and the other lying down, prosecutors said.
The two men had grown close and developed a "father-son" relationship, local residents said.
Many were relieved to discover that they had died of natural causes, reports said.
"It's clear that it did not involve an external intervention," one neighbour told Le Parisien newspaper.
"They did not have enemies, lived simple lives and were not types who would get themselves killed by the mafia," she added.
Squatters who had taken over a disused power station owned by Oxford University have vacated the building.
[NEXT_CONCEPT]
Post-mortems in France have explained the mystery of how two men found dead together after a meal perished.