A demonstration has been held outside a council meeting where a petition demanding licensing of private landlords in Brighton and Hove was discussed.
The document, signed by more than 2,000 people, calls for reforms including "fairer" rents and five-year tenancies.
The Living Rent Campaign said almost a third of homes in the city were privately rented.
It said some tenants spent two thirds or more of their wages on rent.
The campaigners said average monthly private rents in Brighton and Hove were £867 for a one bedroom flat, £1,282 for a two bedroom flat and £1,537 for a three bedroom house.
The group said more than 30% of homes in the city were privately rented, almost double the national average, and house prices were 44% higher than the national average.
'Half my wages'
Private tenant Zoe, who did not want to give her her surname, said rents were "spiralling out of control".
"I think it's absolutely imperative to get some form of regulation," she said.
"I'm 36 years old. I've been renting since I was 18 and during that period I've moved around 10 times."
She said she paid £495 a month for a 15 sq m studio flat in Brighton.
"I'm spending nearly half of my wages on rent alone," she said.
"I'm actually in a better position than a lot of other people who are paying a lot more and perhaps have children and more responsibilities."
Campaign coordinator David Gibson said: "The 'living wage' spearheaded by the council and local chamber of commerce, though commendable, is of little use to people without a living rent.
"We are asking the council to develop an ethical landlord scheme with fairer rents and a good standard of property maintenance enforced by a licensing scheme for private landlords."
He also called for the authority to establish an "ethical" lettings agency. The petition is also calling for the the government to institute controls on private sector rents.
"Tenants tell us they are too frightened to ask for much-needed repairs in case landlords put their rent up or use this as an excuse to evict them," he said.
Gavin Dick, of the National Landlords Association, said: "As a university town, and with excellent transport links to London and across the South East, Brighton is a high demand area and the growth of privately rented housing in the region over the past decade is broadly in line with the wider growth of the sector.
"While default five years tenancies and artificial suppression of rents sound like easy solutions, they will only be counter-productive to encouraging the supply of more housing in the long term."