The studio was founded in February 4, 1960 by Daisuke Shinada as Shinada-sha (Kanji: 品田社) and made its first anime later that same year: Blanc & Yamada's English-Japanese Seminar. Over the course of the 60's, many anime shorts, movies and TV series would follow.
In 1978, film production company Shochiku bought the studio and introduced several new staff members.
After the death of Daisuke Shinada in 1981, his two then-22 year old sons Takuya and Taiyo Shinada inherited the company and renamed it to Studio XYZ, and currently still produces anime to this day.
There's a wide grade of confusion around how Studio XYZ is pronounced, particularly the XYZ part, as it's often pronounced either "kseez" or "X-Y-Z" in English and "ekkusu-wai-zetto" (エックス・ワイ・ゼット) in Japanese.
However, the official Japanese romanization of the studio's name is "sutajio batsu-wai-zetto" (スタジオバツ・ワイ・ゼット). This can be confirmed by XYZ-tan's Japanese name being pronounced "batsu-wai-zettan".