Marco Trungelliti has received support from the Tennis Integrity Unit more than two weeks after complaining of feeling abandoned after blowing the whistle on match-fixing in the sport.
The 29-year-old world number 130 acted as a witness in last year's prosecution of three fellow Argentine players for gambling-related activities.
He said he was criticised for his actions, with his motives questioned.
But the TIU says he acted with "the best interests of the sport" in mind.
"His courageous and principled stand against those who seek to corrupt is to be admired and commended," the organisation added in a statement.
The three tennis players sanctioned former world number 78 Nicolas Kicker, ex-world number 269 Patricio Heras and Federico Coria, whose career-high ranking is 223.
Last June, Kicker was banned for six years, with three of those suspended, while Heras was banned for five years, with two suspended. Coria was banned for eight months, with six months suspended.
Trungelliti, who famously drove all night from Barcelona to Paris to claim a place in the main draw of the 2018 French Open, subsequently found himself shunned by some of his fellow professionals and said he repeatedly asked without success for the TIU to support him.
The TIU explained in their statement why they had not publically defended Trungelliti earlier.
"As part of its confidentiality policy, the TIU's intention is at all times to protect the identity of witnesses, and in line with that has not commented on or confirmed Mr Trungelliti's involvement in these cases," they said.
"However, the TIU understands that Mr Trungelliti has subsequently been subject to strong personal criticism and that his motives for co-operating with the TIU have been questioned.
"The TIU unreservedly condemns the treatment received by Mr Trungelliti and would like to place on record its appreciation of his support and full compliance with the Tennis Anti-Corruption Program."