He claims his contract was "wrongfully terminated" and is reportedly asking the court to award him damages in excess of $25,000.
The personal assistant was sacked in January for "serious misconduct," according to a spokesman for the couple.
The former Take That singer married Miss Field in 2010 in the grounds of his Beverly Hills mansion after four years together.
Multi-millionaire Williams gushed about life with his energetic wife in an interview last year.
"I love my wife's company," he told The Telegraph. "She gives me a lot of energy - she's like a one-woman cheerleading team.
"When you're bored you get lonely, but fortunately I don't have to be because my best friend is with me. We get on very well and she keeps me entertained.
"She has anchored my life and made me feel secure, and saved me from a life of self-destruction."
In the past Williams has battled alcohol and drug addictions.
The couple have two children together, a two-year-old daughter, Theodora Rose, and son Charlton Valentine, who was born in October last year.
A spokesman for Williams said: "The claims being made by a disgruntled former employee, after he was sacked for serious misconduct, are entirely without substance.
"Any proceedings will be strenuously defended. There will be no further comment on the matter as it is in the hands of the lawyers."
Elsewhere, Williams is embroiled in a dispute with Led Zeppelin rocker Jimmy Page over plans to revamp his multi-million pound home in West London.
The Angels hitmaker has submitted plans three times to modernise and extend his £17.5 million townhouse in the capital.
Williams wants to lower some of the floors in his 46-room mansion and knock down a number of the walls to create bigger rooms and doorways.
But Page, 71, has strongly opposed all of his proposals, claiming work will put his beloved Grade I listed Tower House next door at risk.
- Daily Mail
