Blakeley previously worked in various PR roles over 15 years at the Guinness, Johnnie Walker and Baileys owner, becoming head of alcohol in society, Diageo Western Europe, in 2014.
In July 2015 she became deputy MD of Buckinghamshire-based PRWeek UK Top 150 agency Cirkle. The agency has been led since the start of 2014 by MD Ruth Allchurch, who left a senior Diageo PR role in 2013.
Blakele returned to Diageo earlier this month as head of alcohol in society for Europe, covering during Aileen Keyes' maternity leave. She reports to Allison Dowling, corporate relations director for Diageo Great Britain, in the CSR role.
Allchurch said: "Kate joined Cirkle over a year ago from an in-house role at Diageo where she was for 15 years and she has made the decision to leave agency life and return to her in-house role. We wish her all the very best in the future."
Diageo recently appointed Teneo Blue Rubicon to take over from Edelman as its global corporate comms firm. Portland took Diageo's UK corporate and public affairs brief, which had also been held by Edelman since 2010, in summer 2015.