Mantzoukas will make a guest appearance on the ABC comedy's current season as a fashion designer, Entertainment Weekly reports.
His character will become a co-worker and later boyfriend of Haley (Sarah Hyland).
Mantzoukas has previously appeared on FX comedy The League, HBO's Enlightened and NBC's Parks and Recreation.
His League co-star Paul Scheer has also signed up for a role on Modern Family this season, playing a Costco manager who crosses paths with Gloria (Sofia Vergara) and Claire (Julie Bowen).
Other stars confirmed for the comedy's fourth run include Matthew Broderick and returning guest actress Shelley Long, who plays the ex-wife of Jay (Ed O'Neill).
Modern Family airs on Wednesdays at 9/8c on ABC. In the UK, Sky1 airs the show on Fridays at 8pm.
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Watch a promo for season four of Modern Family below: