Alexa Clark joins from the Cabinet Office, while Johnny Gibson is moving across from Eclipse Marketing.
Clark was most recently the brand and marketing strategy director at the Cabinet Office. She has previously worked alongside the Department for Education and Skills as well as the police and the NHS.
Gibson, meanwhile, joins 23red as its head of direct marketing. He previously worked at JWT/rmg black cat, Saatchi Direct and Bates.
Jane Asscher, the managing partner at 23red, said: "Since our launch, we have gathered some enormously valuable public sector experience. Alexa's appointment is a key part of this - she is well-versed in the unique challenges that the public sector presents. Johnny has an outstanding track record with some of the best agencies in the business, and virtually unrivalled experience at this level."