Vallance, who co-founded Embrace in 2006, has also been executive creative director at Vibrandt (now 1HQ), creative director at Dragon Rouge and creative director at Landor in its London and San Francisco offices.
His appointment follows the move earlier this year to unite Holmes & Marchant with fellow Media Square design consultancy Lloyd Northover.
The move sees both consultancies continuing as individual brands but sharing back-office facilities and with a new management team overseeing both.
John Mathers, who joined Holmes & Marchant as managing director in 2009, has taken over as chief executive of Holmes & Marchant for the UK and Europe, with Simon Gore joining from Lewis Moberly to take over as managing director of Holmes & Marchant UK.
Vallance, who starts on 26 October, will work alongside Gore, with whom he previously worked at Vibrandt.
Vallance will take overall responsibility for Holmes & Marchant’s creative team, working with deputy creative director Richard Hunt. Vallance says, ‘The team has won a number of fantastic projects lately which I can’t wait to get cracking with.’