Jack Dromey MP, Labour's shadow housing minister, described the findings as “shocking” and blamed the government for standing by and doing nothing.
He said: “Unscrupulous lettings agents are ripping off tenants by charging them fees they didn't know they would face, and exploiting landlords and tenants alike by failing to protect the money they hold for them.
"As the growing housing crisis and double dip recession put the one million families in the private rented sector under pressure, this is the last thing they need.”
In Shelter's survey, 23% - equivalent to 11 million people - said they had been charged unfair fees, commonly for administration, credit checks and contract renewal, when renting through a letting agent in England.
More than half felt the fees were unfair because they were disproportionate to the cost or amount of work done by the letting agent.
Angelique, a renter from Hampshire, said: “‘We didn't receive any justification for these extortionate fees, and ended up having to pay nearly £3,000 upfront, making a huge dent in our finances.
“I have nowhere I can complain to and be taken seriously. The rental market is a horrible place right now.”
Kay Boycott, Shelter's director of campaigns, policy and communications, called the actions of these agents “scandalous”.
He said: “They are creaming off huge profits from the boom in private renting, it’s no surprise that many dread the day they have to look for a new place to rent.”