The Citizens Advice Bureau (Cab) in Inverness and Highland has blamed unprecedented demand for being unable to continue staffing the tribunals.
Its counsellors will offer guidance but no longer personally attend because, it says, welfare reforms and mounting public debt has left it overstretched.
Four specialists usually help about 30 disabled people a month at hearings and Cab Inverness, Nairn, Badenoch and Strathspey manager Alasdair Christie said it was "heartbreaking" to have to withdraw that support.
"We’d need an increase in funding of about £80,000 per year to maintain that service," he said.
"We will supply written submissions and support to clients but won’t be able to represent clients personally, simply because we don’t have enough staff. It’s heartbreaking and not a decision we’ve taken lightly."
Mr Christie added Cab would be looking to third sector partners to pick up the support element for meetings and said the change would not affect the overall number of clients it sees.
Benefits tribunals are usually held after personal independence payments, employment support allowance payments or universal credit payments have been stopped or reduced.
The Cab Highland branch has a current annual budget of £1 million and recently moved from Academy Street in Inverness to more spacious premises in Union Street.
It denied the move was an unnecessary extravagance however, as its nine interview rooms – up from three – means they can see more clients. The branch employs 36 paid staff and has 60 volunteers.
Mr Christie said the service "saved governments and councils a lot of money through early intervention in areas such as lost benefits."
Severely physically disabled Donna Macdonald (45), from Inverness, is one of those now facing the prospect of a benefits tribunal in May without Cab representation.
She is appealing a cut in benefits from £564 to £311 a month and said: "I can speak up for myself, but it will be a challenge.
"Citizens Advice have been brilliant in supporting people in their time of need. Without their support where would people go?
"I think the government should pay for someone to support disabled people at tribunals."
Another woman, who did not wish to be named, successfully won a previous appeal thanks to the help of Cab and MP Drew Hendry.
She said: "The system can dehumanise you, and the Cab is there for you when you fall. I dread to think what’s going to happen to people without that support."
Mr Hendry said: "The support they give to families with nowhere to turn has been nothing short of heroic.
"That our local Cab has had such a high success rate in overturning appeal decisions highlights how unfair the system is and how valuable their work is.
"Its decision will have been extremely difficult to make. I’ll do everything I can to support them and those who will be affected."
A UK government spokeswoman said: “Since PIP (personal independence payment) was introduced 3.1 million decisions have been made. Of these, nine percent have been appealed and four percent have been overturned.
"In the majority of successful appeals, decisions are overturned because people have submitted more oral or written evidence. Legal aid is available to those who need it and last year we spent over £1.6 billion on support.”