LONDON — Boris Becker, the six-time Grand Slam tennis champion, was sentenced to two and a half years in prison on Friday in his bankruptcy case, after he was found guilty by a London court of hiding millions of dollars’ worth of assets and loans to avoid paying his debts.

The sentence punctuated a startling fall from grace for Mr. Becker, 54, who parlayed his tennis skill, ebullient personality and business ambitions into a personal fortune before he was found guilty this month at Southwark Crown Court of four charges related to his June 2017 bankruptcy.

The bankruptcy case meant Mr. Becker was legally obliged to disclose all of his assets so that they could be used to pay his creditors, but the court found several instances in which he failed to meet his obligations for disclosure.

Mr. Becker failed to disclose a property he owned in his home country of Germany, concealed a loan of €825,000 (around $872,000) and assets valued at €426,930.90, and did not disclose shares owned in a gambling tech firm, according to Britain’s Insolvency Service. He was acquitted of 20 other counts relating to his bankruptcy.

Mr. Becker made tennis history in 1985 when at age 17, he became the youngest champion in the history of men’s singles at Wimbledon. He went on to win there two more times, in 1986 and 1989, and took three other Grand Slam singles titles: the U.S. Open in 1989 and the Australian Open in 1991 and 1996. He retired from professional tennis in 1999.

The tennis star was the subject of enormous attention not just for his success on the court. The tabloids also kept a close watch on his tumultuous love life, including a divorce and a fleeting affair with a Russian woman with whom he fathered a child.

The precarious financial situation of Mr. Becker has been under scrutiny for several years.

In 2017, a private bank in London, Arbuthnot Latham, made an application for bankruptcy proceedings against Mr. Becker, claiming that payment of a large debt owed by him was nearly two years overdue. He was soon declared officially bankrupt by a London court, which found that he could not repay his debts.

That same year, a Swiss court rejected a claim by a former Swiss business partner, who claimed Mr. Becker owed him more than $40 million.

As he fended off his creditors, in 2018, Mr. Becker sought to claim diplomatic immunity, because the Central African Republic had named him as its attaché to the European Union for sports, culture and humanitarian affairs.

If that claim had been granted, any action against Mr. Becker would have required the approval of the foreign secretary, who at the time was Boris Johnson, the current prime minister. But Mr. Becker eventually dropped the claim.

In 2002, Mr. Becker was convicted in Germany of income tax evasion, given two years’ probation and fined nearly $300,000. The verdict came six years after German tax investigators raided Mr. Becker’s home in Munich.

Mr. Becker is said to have won millions of dollars in prize money and sponsorship deals. He has had several business ventures over the years, including a line of branded tennis gear. He has often appeared as a television commentator for the BBC at Wimbledon, and he coached Novak Djokovic, the world’s top-ranked men’s singles player, for a few years.