A defiant Becker said he was "immensely proud" of his new role – and attacked the "bunch of anonymous and unaccountable bankers and bureaucrats" who are chasing him for money.
He said he had "asserted diplomatic immunity as I am in fact bound to do, in order to bring this farce to an end, so that I can start to rebuild my life".
According to the 1961 Vienna Convention, this means that he cannot be subject to legal process in the courts of any country for so long as he remains a recognised diplomatic agent.
He now cannot be sued for the cash without the consent of the Central African Republic, while legal claims can only be served on him through diplomatic channels.
Any legal action would also require the agreement of Foreign Secretary Boris Johnson as well as the Central African Republic's foreign minister.
Becker's decision to become a diplomat could mean that none of the money he is expected to receive for commentating for the BBC at Wimbledon will go to his creditors.
Experts said that anyone could become a foreign diplomat in this way if invited to do so by the country, and assert diplomatic immunity.
Becker said in a statement: "A bunch of anonymous and unaccountable bankers and bureaucrats pushed me into a completely unnecessary declaration of bankruptcy, which has inflicted a whole heap of damage on me, both commercially and professionally, and on those close to me.
"I have now asserted diplomatic immunity as I am in fact bound to do, in order to bring this farce to an end, so that I can start to rebuild my life.
"Once this gravy train for the suits has been stopped in its tracks, my lawyers will turn to the question of compensation.
"I will be coming after the people who forced this process through to hold them publicly accountable for their actions."
Becker said he was "immensely proud of my appointment at the Sports and Culture Attache for the Central African Republic.
"Sport is incredibly important in Africa and is fast becoming a universal language, a form of social diplomacy and a leveler between people from vastly different and unequal social backgrounds around the world.
"My diplomatic role in the Central African Republic allows me to give something meaningful back to sports supporters in one of the poorest parts of the world.
"There is no reason why a role of this kind should be treated any differently to an appointment as a military or a trade attache, which everyone recognises as attracting diplomatic immunity."
Becker has hired Ben Emmerson QC, a leading human rights lawyer who has acted in the past for Wikileaks Julian Assange, to handle his claim for diplomatic immunity.
Mr Emmerson is a former United Nations Special Rapporteur and currently sits as a judge on several U.N. International Tribunals.
In May Becker split from his wife of nine years. The German former tennis star and Dutch model Lilly, 41, took what "wasn't an easy decision", their lawyer said, having this year revealed the strain his financial problems were having on their marriage.
The BBC did not comment. A spokesman for one of his creditors Arbuthnot, Latham & Co declined to comment.
Becker won his first Wimbledon title, aged 17, in 1985. Two more Wimbledon titles followed in 1986 and 1989, as well a US Open in 1989 and the Australian Open in 1991 and 1996.
During bankruptcy proceedings in London last June, John Briggs, Mr Becker's lawyer, told the court: "He is not a sophisticated individual when it comes to finances."
His bankruptcy followed a run of bad luck, including £20million in divorce and paternity settlements to his first wife, Barbara, and Angela Ermakova, a Russian model, and a two-year suspended sentence for tax evasion.
There were also claims in Germany's Spiegel magazine that Becker may have lost his £100million fortune in part because of questionable investments in the Nigerian oil industry. Becker did not comment on these claims at the time.
Experts told the Telegraph that anyone could become a foreign diplomat in this way if invited to do so by the country, and assert diplomatic immunity.
