Dariush was born in Tehran, Iran and spent some formative years in Germany and London. In 1979, he and his family moved to Alexandria, VA (that delightful suburb of Washington, D.C) where he grew up. He's a graduate of Bishop Ireton High School, received his undergraduate degree from George Washington University and an MFA in Acting from Rutgers University, Mason Gross School of the Arts.

Most recently, he appeared in Lincoln Center's Oslo (by J.T. Rogers, directed by Bartlett Sher), winner of the 2017 Tony Award winning production for best Broadway play. Oslo's sweep of the 2016-2017 awards season included the New York Drama Critics Circle, Lucille Lortel and Outer Critics Circle Awards for Outstanding New Broadway Play. Kashani also earned an Obie Award along with company of Oslo for Best Ensemble.

Off-Broadway, he's appeared in The Invisible Hand by Ayad Akhtar (directed by Ken Rus Schmoll) at New York Theatre Workshop; The Happiest Song Plays Last by Quiara Alegría Hudes, directed by Ruben Santiago-Hudson at Second Stage Theatre in New York City. His work in Tony Kushner's Homebody/Kabul began with the premier at New York Theatre Workshop (directed by Declan Donnellan) and continued with subsequent productions at Mark Taper Forum and Brooklyn Academy of Music, both directed by Frank Galati. Other plays include East is East by Ayub Khan-Din (Manhattan Theatre Club), Naomi Wallace's The Retreating World (McCarter Theatre & Cooper Union) and Amadeus, directed by Hal Scott.

On Television, he's appeared in "Madam Secretary," "Franklin & Bash," "NCIS: Los Angeles," "Law & Order," "CSI," “Ghost Whisperer," "NCIS," "Medium," "Drive," "Lost," "24," "JAG," "Without a Trace," "Law & Order: Criminal Intent," and "Guiding Light." Currently, he's working on AMC’s new darkly comedic drama, "Dietland," based on Sarai Walker’s novel.

Dariush lives in New York City.