He spent money from his business account on his children's school fees, designer clothes and shopping at the luxury store, Harrods, jurors heard.
The 54-year-old, who commentated for the BBC last year, is on trial at Southwark Crown Court charged with 24 offences under the Insolvency Act.
He denies all charges.
The charges relate to his June 2017 bankruptcy over a £3.5m bank loan for a property in Mallorca, Spain.
He is accused of hiding, or failing to hand over, assets before and after his bankruptcy.
As the second day of Mr Becker's trial got under way, the jury heard the former world number one spent hundreds of pounds at Harrods, bought online groceries at Ocado and treated himself to Ralph Lauren clothes.
The German national is alleged to have hidden €1.13 million (£940,000) from the sale of a Mercedes car dealership he owned in Germany, which was paid into his Boris Becker Private Office (BBPOL) account.
Prosecutor Rebecca Chalkley said: "It is the prosecution case that Mr Becker used the BBPOL sterling account as an extension of his own account, effectively as his own piggy bank, for everyday personal expenses such as school fees for the children and such like."
She said payments in 2017 included £643 to Polo Ralph Lauren, £7,600 in school fees, £976 at Harrods and more than £1,000 at Ocado.
Ms Chalkley told jurors Mr Becker paid his ex-wife Barbara Becker €23,000 (£19,000), estranged wife Sharell "Lilly" Becker €100,000 (£83,000) and transferred £225,000 to a friend.
The prosecutor added that he also transferred €300,000 (£249,000) to his own account, while other funds went into an account he jointly held with his son.
Mr Becker is also accused of failing to hand over assets including trophies he received as a result of his 1985 and 1989 Wimbledon men's singles title, his Australian Open trophies from 1991 and 1996 and his 1992 Olympic gold medal.
He also allegedly failed to declare two German properties, as well as his interest in a flat in Chelsea, west London, and hid a €825,000 (£686,000) bank loan.
The prosecution is being brought by the Insolvency Service on behalf of the business secretary.
On Monday at the start of the trial, Judge Deborah Taylor instructed the jury of 11 men and one woman to ignore Mr Becker's celebrity.
"You must treat him in exactly the same way you would treat someone you have not heard of and is not in the public eye," she said.
The 24 charges include:
* Nine counts of failing to deliver up trophies and other awards;
* Seven counts of concealing property totalling more than €1.5m
* Five counts of failing to disclose estate, including the properties in Germany and London, shares and a bank account
* Two of removal of property amounting to almost €500,000
* One of concealing €825,000 of debt
The trial, expected to last up to three weeks, continues.