Malcolm Macaskill, whose removal paved the way for new party leader Ruth Davidson to get to Holyrood, got the five-figure pay-out after threatening to sue over the Tories' handling of his sacking.
In an interview with the Sunday Herald, Macaskill blasted the Tory machine as "rotten to the core" and said the Scottish party was an "inept and morally corrupt" organisation.
Macaskill, a member of the Scottish Tories for 35 years, was top of the party's Glasgow list for last year's Holyrood poll – almost guaranteeing him a seat in Parliament. However, days before the start of the campaign, party bosses removed him from the list amid allegations of historical financial problems.
Davidson took his place on the list and was subsequently elected to Holyrood and then as party leader.
Following the election, Macaskill served notice on Davidson that he intended to seek a judicial review of his dismissal, and claimed the meeting which led to his removal did not have the minimum number of officials present to make the ruling.
He also insisted party rules did not contain any provision to remove a list candidate, thus he believed the party had acted unconstitutionally.
The Sunday Herald understands that discussions between lawyers representing Macaskill and the Scottish Tories led to an out-of-court agreement earlier this year.
Although Macaskill had been pursuing the party for an apology, it is believed the Conservatives gave him a five-figure sum.
Speaking to the Sunday Herald, Macaskill said of the resolution: "I regret that I am unable to confirm or deny if such an agreement exists."
However, he confirmed that he had recently quit the party. He said: "All I ever wanted from the party was an apology. An admission that they were wrong in dismissing me and that they had on this occasion failed to follow their own procedures. This was never forthcoming.
"After discussions with my family, friends and legal team, I decided not to go to the Court of Session. This decision was made because I have now decided that I've had enough of the Tory Party."
He said of his experience: "Over the past year, the treatment that I have been subjected to, along with the evidence that I have gathered, has convinced me that the party machine in and around Edinburgh central office is rotten to the core.
"I no longer wish to remain a member of such an inept and morally corrupt organisation."
On Davidson's leadership, Macaskill said her comments about drawing a "line in the sand" over devolved powers to Holyrood had damaged her position. Prime Minister David Cameron later said more powers could be devolved.
"It remains to be seen how she will fare as leader. Early signs are not promising. The 'line in the sand' contradiction from David Cameron was embarrassing and severely undermined her authority.
"I can't help but feel that the leadership role requires greater experience and that it may have been better suited to any one of the other three candidates."
On the fact his removal saw Davidson get top place on the Glasgow list, he said: "Some have suggested that there was perhaps always a greater plan. In dismissing me, the next in line on the regional list was Ruth Davidson, who had earlier failed to be selected as a constituency candidate in other parts of Scotland.
"History shows that not only was Ruth elected in my stead, but she also went on to become the party leader in Scotland."
He added that he did not foresee a successful future for the party: "I know of hundreds of people who will never vote Tory again."
Bob Doris, SNP MSP for Glasgow, said: "The Tories don't know if they are coming or going when it comes to Scotland. No wonder Mr Macaskill has walked out on them. You might think it wasn't possible for the Tories to sink any further but that is exactly what is happening here."
A spokesman for the Scottish Conservatives said: "The position of the party remains that Mr Macaskill was not a fit and proper person to be a Conservative candidate. He had failed to disclose a succession of business failures to the party and when these were discovered the party took action.
"Given the proximity of the decision to the Scottish Parliamentary elections the party accepts that Mr Macaskill sought legal advice and the party, as a gesture of goodwill, contributed to these costs."
Macaskill denied failing to reveal "business failures" to the party.