O.J. Mayo's Milwaukee Mansion in Foreclosure, Owes $1.1 Million

O.J. Mayo is close to losing his massive, million dollar mansion in Milwaukee ... 'cause the bank claims the ex-NBA star hasn't made a payment in 10 months ... TMZ Sports has learned.

Here's what we know ... O.J. bought a $1.8 million home in Wisconsin after inking a 3-year, $24 million deal with the Bucks in 2013. At the time, Mayo took out a loan for $1.26 million to help pay for the crib.

The place is SICK -- 9,200 square feet with 5 bedrooms, 4.5 baths, home theater and private gym.

But, according to court docs obtained by TMZ Sports ... Mayo stopped making payments in April 2018 while still owing $1,137,302.42 on his mortgage.

A few months later, the bank foreclosed on the house to get their dough back.

The bank tried to serve Mayo with court documents several times -- but they were unsuccessful. Eventually, Mayo's trainer told a process server that O.J. is currently playing overseas in China.

It's unlikely Mayo is hard up for the cash since he reportedly made $45 MILLION during his 8 years in the NBA before getting hit with a ban for violating the league's anti-drug policy in 2016.