The Civil Aviation Authority (CAA) said the airport was the only one to have a “poor” performance.
It criticised both Amey, the firm which was responsible for the mobility service.
The CAA also rebuked airport managers for failing to check how well the company was looking after 50,000 such passengers a year.
Amey, which had promised “best in class” service when it was awarded the £3 million contract three years ago, had it terminated in March.
The CAA said improvements with the assistance service were also needed at Aberdeen, Inverness and Prestwick airports.
Glasgow was the only one airport in Scotland to be rated “good”.
The CAA said it had consulted widely with a number of
disability organisations consistently provided a good
Assistance for disabled passengers includes for checking in, transferring to boarding gates and onto aircraft, and helping arriving passengers reach onward transport.
The CAA said it had raised concerns with Edinburgh Airport last November, including because of the “lack of proper oversight” of Amey’s performance.
It said the airport had since replaced Amey with OmniServ, and significantly increased the budget to buy new equipment and provide more staff.
The airport had also appointed a new manager to ensure the service improved.
When Amey won the contract in 2013, its then chief executive Mel Ewell said: “Building on our proven expertise in airport management, we will introduce innovations and best practice to deliver efficiencies for the client as well as a best in class service for airport passengers”.
The CAA said: “We welcome the steps Edinburgh Airport has taken and we will continue to monitor the airport’s performance closely.”
An airport spokesman said: “Since the findings of this report were collected six months ago we have taken great steps to improve in this area, including bringing in OmniServ, who won a three-year contract to undertake the provision of services for persons with reduced mobility.
“Edinburgh Airport is absolutely committed to continuing to improve the passenger experience of everyone who uses the airport, including those with a disability and those with reduced mobility.”
The report also highlighted that Aberdeen Airport had repeatedly missed its arrival performance targets last year but performance had since improved.
It criticised other airports, including Inverness and Prestwick, for failing to show they had consulted with disability groups, but said it was pleased they planned to do so.
A spokesman for Highlands and Islands Airports, which runs Inverness Airport, said: “We are grateful the report recognises the ‘taking steps’ rating for Inverness Airport has more to do with the communication around what we have been and are doing around accessibility at the airport, rather than any failings on our part in what has always been an important area of consideration for everyone at HIAL.
“We are already taking steps to improve communication around accessibility on our website and other airport communication channels, and are confident those changes will be reflected in a much higher rating next year.”