[1][2] Patsy Lou Blake was born in Fort Worth, Texas and grew up further east in nearby Dallas.

In 1962-1963 she starred as newly-arrived hotel operator "Lou Mallory" in the later seasons of the Western The Rifleman, (replacing general store keeper "Milly Scott", played by actress Joan Taylor) as North Fork, New Mexico Territory rancher "Lucas McCain" (star Chuck Connors)'s new occasional love interest on that long-running series.

She made guest appearances as well on other television series, such as The Bob Cummings Show; Rescue 8; Gunsmoke; Richard Diamond, Private Detective; The Virginian; and Bonanza.

Blair had considered moving to New York City in 1964 until screenwriter Gordon Chase helped her get a role on the NBC series Daniel Boone (1964-1970).

Her last appearance in a feature film was in 1979, portraying a fashion narrator in The Electric Horseman starring Robert Redford.