In papers filed at Los Angeles Superior Court on 3 July and seen by the AP news agency, Debbie Rowe seeks an immediate payment of $195,000 (£106,000).
She also requests $50,000 (£27,250) in living expenses so she can pursue a child custody case against Jackson.
Rowe is the mother of his two children, now aged eight and nine.
In a 2001 agreement, she waived all access rights to the children, Prince Michael and Paris.
Debbie Rowe testified at Jackson's child abuse trial last year
Last year, Rowe, who divorced Jackson in 1999, testified at the singer's child abuse trial, praising him as a "great father".
But in her new legal action, she claims he stopped making the promised payments in October 2003.
Jackson, 47, is also being sued by a former business associate, Marc Schaffel, who claims he is owed $3.8m (£2.1m).
The jury in that case in Santa Monica, California, heard closing arguments on Wednesday and is expected to retire on Thursday.
Mr Schaffel's attorney Howard King called Jackson a "cagey, calculating witness" who feigned forgetfulness in videotaped depositions shown to the jury.
The pop star's own legal representative has painted a different portrait of the troubled singer.
"I don't see the evil, conniving puppet master he saw," Thomas Mundell said. "I saw the gentle, easily influenced artist who pays little attention to business matters."Last Mod: 20 Eylül 2018, 18:16