Katie's got backup - and she's not leaving home without it.

Katie Holmes emerged from four days of seclusion in her Chelsea pad yesterday - her first public appearance since filing for divorce from Tom Cruise - surrounded by a pack of beefy security guards.

She flexed the heavy muscle amid fears she's being stalked by Scientology officials because of her bombshell split from church member Cruise - and concerns he might try to kidnap their daughter, Suri, 6, sources told The Post.

Holmes wore a blue button-down, long-sleeved dress but was missing a key accessory - her wedding ring.

She smiled faintly and cast her eyes down as she exited a black Mercedes-Benz sedan with Florida plates in front of 66 Seventh Ave. in Chelsea at about 9 a.m.

She was there for a scheduled appearance on the reality-TV show "Project Runway: All Stars."

Flanked by her crew of rent-a-cops, Holmes walked into Parsons The New School for Design, where the Lifetime show tapes.