Ellis spent four years at Firefly, where she reported to head of corporate Jon Holt in the agency's business technology practice.
At GCI she reports to CEO Mark Cater, who said her focus would be ‘to expand GCI's technology and consumer technology portfolio'. He added that the role had been created as a result of account wins with as yet undisclosed clients.
Ellis will also work on the firm's tech account with Dell and sat nav brand Garmin.
Ellis's PR career began at Text 100 in 1995. She has previously worked at Golin Harris, Weber Shandwick and Brodeur Worldwide (now Pleon).
GCI has also hired Amanda Symons as account manager. She joins from Mantra PR, where she was a junior account manager. She will work on GCI's BAA and Mates accounts. Mantra is recruiting for a replacement.
Firefly CEO Claire Walker said she had not directly replaced Ellis but had hired senior account director Christine Wilkie, previously of GCI, and account director Siobhan Gilheany, from Fishburn Hedges.