The Glee star - who plays Rachel Berry in the show - sizzled as she walked the red carpet ahead of the first screening of TV series American Horror Story: Freak Show in Los Angeles.
Flashing her gym-honed bod, Lea sported a teal coloured velvet dress by Cushnie Et Ochs which featured a super-deep V-neckline, a saucy thigh-high slit and a figure-hugging bodice.
The actress teamed her daring dress with barely-there silver strappy heels and a boxy clutch bag, adding dainty drop earrings and a delicate diamond-encrusted ring.
Her brunette locks tumbled past her shoulders in voluminous curls and she decorated her brown eyes with charcoal grey smoky eyeshadow and jet black mascara, finishing with a dab of nude lipgloss and bronzed-up cheeks.
American Horror Story is actually produced by Glee creators Brad Falchuk and Ryan Murphy, so it's hardly surprising Lea turned up to support them.
And a few of her Glee co-stars were present on the evening too, including Chord Overstreet (who plays Sam Evans), Kevin McHale (Artie Abrams), Becca Tobin (Kitty Wilde), Darren Criss (Blaine Anderson) and Jacob Artist (Jake Puckerman).
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