Barr replaces Rita Broe, who was promoted to head European marketing for the MasterCard group last September.
She will report to Hany Fam, general manager of MasterCard UK & Ireland.
Barr will work with Ben Rhodes and Andrew Miles, head of brand marketing and customer marketing respectively.
She says her priority will be to ensure MasterCard’s marketing strategy drives “even higher levels of consumer engagement with the brand.”
The company is to use its sponsorship deals with the Rugby Union Word Cup, UEFA Champions League and the Brit Awards to showcase its products to customers this year.
Barr left John Lewis last March after the retailer temporarily cut the position of marketing director.
Prior to joining John Lewis, Barr’s previous positions include business development director at Woolworths, director of proposition development at Superdrug and senior retail consultant at KPMG.