Alexandra Wrage, who served on FIFA's independent governance committee, which was set up to advise on reform after allegations of corruption in the organisation, said she saw no point in continuing her work.
FIFA were not immediately available for comment.
Wrage told Reuters on Monday: "We all work to be effective, when you can't have an impact, or you reach a position where you don't believe you can have an impact then you move on to things where you can.
"I was not having an impact on FIFA governance," added Wrage, who is president of TRACE International, which specialises in anti-bribery compliance. It was an interesting process with a committed team but the FIFA response to the governance recommendations was fairly breathtaking frankly."
Her resignation is not a complete surprise as earlier this month, IGC chairman Mark Pieth stated publicly his committee were running into some FIFA roadblocks.
"We were asking for independence in the executive committee, but they're terribly afraid of that," he told the Daily Telegraph.
"It's one of the major challenges. We've said you need to look at the board of a corporation, with independent directors."
Canadian Wrage said that after initial support for some of the IGC's proposals she gained the impression, from his public statements, that FIFA president Sepp Blatter was not committed to further, serious, detailed reforms.
"I think Blatter has sent a very strong message that the reform process is wrapping up, the mission has been accomplished and that they can declare themselves reformed," she added.
"Discussions about the potential for self-dealing and conflict of interests and transparency around compensation become a little more interesting in light of the CONCACAF Integrity Committee report on Friday and still with that kind of track record to be resisting fairly benign, straightforward improvements means that there isn't really any more work for me to do here," she continued.
"You say, here are some good, solid steps in the right direction and you are met with no, no and no. So, you say, more of this doesn't sound very rewarding."
Among the proposals put forward by Wrage which she says were rejected by FIFA were neutral, independent, centralised vetting on new candidates for the executive committee with FIFA preferring self-declaration, according to Wrage.
She said proposals for disclosures on compensation were rejected outright by the executive committee.
She added that policies on term and age limits were going to be simply put to FIFA's congress of its 209 member nations without any prior work or recommendation from the executive committee.
"There were certainly some things accomplished in the first year - the split in investigative and adjudicatory bodies (on the Ethics Committee), those sorts of things are progress.
"Where you lose the public's attention on the kind of nitty gritty compliance issues that are incredibly important structurally, to make sure there are systemic safeguards in place going forward, those were rejected," said Wrage.
The IGC, under the chairmanship of Swiss lawyer Mark Pieth, a professor in criminal law, is preparing to present its final recommendations for change to the Congress in Mauritius at the end of next month.
Blatter earlier told InsideWorldFootball that he had asked Pieth and his committee not to make further public comments on the process as it could damage it.
"I am surprised with Pieth's reaction," he said at the time.
"He was asked to make proposals. He was designated by me, and confirmed by the (FIFA) executive committee, to be the chair of what we described, at the time, as the committee for solutions.
"He is to propose solutions. But he thought, or the people around him thought, that all of the solutions that they propose have to be implemented. This is not possible.
"We have to look at them, we have to discuss them and then we will see what will be accepted, or not, by the congress.
"If he is to make criticisms, I have told him that he should not go public, because he is a part of the reform process.
"If everybody in the reform process goes public and says that they are not happy with this and that, there will be a lot of confusion. We have to avoid that."