Rozz Boy is now in charge of the H&K's 20-strong technology practice, reporting to head of corporate Tarquin Henderson.
WPP-owned tech agency Blanc & Otus shut its UK office last week and has consolidated its UK operations into H&K. Two staff were made redundant and one was offered a job at H&K but declined.
The H&K tech team will now handle the accounts for media advertising network Video Egg and software firms NetQoS and Lyris. It will also work closely with the US Blanc & Otus team.
Boy replaces Lee Brooke, who became MD of the Bell Pottinger-owned tech agency Harvard last November.
Boy spent three years at Firefly where she led the LG Electronics account and also led the B2B team that launched UK broadcast platform Freesat into the UK. Prior to Firefly, she headed up Motorola's sub-saharan Africa PR for three years.