Cotterill, an art director, and Hooper, his copywriter, have opted to make the switch after just 16 months at D'Arcy, where they were the creative group heads.
At Lowe they will replace the much decorated team of Mickey Tudor and Brian Turner, who left in May to link up with Charles Inge, Lowe's former creative director, at Clemmow Hornby Inge.
Chris Thomas, the Lowe chief executive, said: "We're always looking for teams who are accomplished at delivering distinctive, talked-about work for mainstream brands. Christian and Justin are one of those teams."
The pair's career spans two spells at HHCL & Partners, where they began working together in 1992. They later spent two years in Hong Kong at Euro RSCG and DDB.
They joined Ogilvy & Mather in 1994, spending five years working on accounts including Ford, Guinness, Lucozade and Unilever's Impulse. Their "art school ad for the deodorant was also a gold winner at Cannes in 1998. D'Arcy hired them from HHCL in March last year to develop the agency's creative product and to satisfy its call for more "talked-about ads".
"They have done outstanding work on major brands, Thomas added. "The fact that Unilever is one can only be to our advantage."
Hooper said: "Lowe is packed with great clients and great creative opportunities."