Ex-Steelers Star James Farrior -- Drops $3.8 MIL on Badass Retirement Mansion

Former Pittsburgh Steelers linebacker James Farrior just bought one SICK place to spend his retirement years ... a $3.8 million mansion in Houston, TMZ Sports has learned.

Sources tell us ... 39-year-old Farrior -- who made at least $35 million during his 14-year NFL career -- locked up a 10,332 square foot palace right next to a golf course.

The mansion comes with 6 bedrooms, 8 baths, an enormous wine cellar, game room, study ... and (of course) an awesome built-in movie theater.

There's also a sweet outdoor loggia -- which is an open air facade of the house that features its own fireplaces (one of four on the property).

It's good to be rich.