Slater's move comes just six months after he was promoted from marketing director to operations director at Charles Russell.
He had been with Charles Russell for four years and said he would be sorry to leave what he described as a “cracking good firm”.
But he added: “This was a serious opportunity which had to be considered very carefully. It is a plum position.”
He will be joining Eversheds from 28 September.
In his new role, Slater will be answerable to Eversheds' executive board, made up of Andrew Latchmore, managing partner, client services, chairman Keith James, Birmingham managing partner Ian Jolley and Victor Semmons, the international director.
Latchmore said the firm had interviewed 70 candidates for the post, which involves the formulation and implementation of the firm's domestic and international strategy.