She was previously heading the magazine section at Mail Newspapers.
Dolphin will replace Abby Carvosso, who will take over as head of magazines at Bauer Media in January. She will oversee the fashion magazine and its website graziadaily.co.uk.
Prior to joining Grazia, Dolphin worked at Associated Newspapers, Clear Channel and Admedia.
Grazian recorded a slight rise in circulation year on year of 1.1 per cent for the period July to December 2009.