Wilkinson, who joins from Zed Media, will bring more than five years of experience to her new role.
At her previous position, she worked on various accounts including telecoms, health and beauty, financial services, automotive and charity.
Prior to this, Wilkinson spent almost four years at independent list broker and manager Hilite.
Darrel Linehan, director of list broking at LJG, said: "We are excited to have Rachel join our list broking division and are confident that her experience and proven track record will be an asset to the team."