Paul Andrew was born in 1979 and grew up in rural England, saving up for copies of Vogue as a child. His father worked as an upholsterer for the British Royal Family, and trips with him to London gave Andrew his taste for fashion; he spent days looking at Christian Lacroix collections with his mother. He studied fashion and showed his first collection at Graduate Fashion Week in London in 1999, when the buyer Yasmin Sewell bought the entire collection, gave him a place to live in London and helped him to his first apprenticeship, at Alexander McQueen.

He moved to New York, working for Narciso Rodriguez, then as a senior designer at Calvin Klein (2000 to 2003) and as vice-president of design for shoes and accessories at Donna Karan (2003 to 2012), some fifteen years in all inside major houses.

He announced his own line of women's shoes for Spring 2013. It was named Launch of the Year by Footwear News, and in 2014 he became the first shoe designer, and the youngest brand, to win the CFDA/Vogue Fashion Fund.

Ferragamo hired him in September 2016 as design director of women's footwear, the founder's own craft. He was promoted to women's creative director in October 2017 and, in February 2019, to creative director of all product categories, the first person to hold that title since Salvatore Ferragamo himself. He showed men's and women's collections together in Milan and oversaw the house's image until he left in April 2021; Maximilian Davis succeeded him in 2022. His own line, paused while he was at Ferragamo, relaunched in 2022 and showed at New York Fashion Week. In July 2024 the Lanvin Group appointed him creative director of the Italian shoemaker Sergio Rossi, with a first collection for autumn 2025.

He has described his aim as shoes that are daring but practical: "something that you can put on your foot and wear and feel confident and sexy and comfortable."

Birth year 1979 is from the Business of Fashion profile; Casadi has not seen a primary record.