The Chime-owned PR agency said the new division, Good Live, would "help brands populate culture by creating entertaining brand experiences from installations and pop-ups to shareable content".
Good Relations CEO Richard Moss said: "Whilst the power of digital communications continues to grow, we are seeing increasing demand from consumers for meaningful physical experiences. Kat is a hugely talented and inventive communications professional, and we’re delighted to welcome her into our fast-growing team."
Day was formerly group account director at Taylor Herring, and before that account director at Mischief PR.
In a separate development, Dove has left Good Relations after his role was made redundant, PRWeek has learned. His position will not be replaced.
In a statement, Good Relations said: "We are restructuring the creative department at Good Relations. As part of this restructure we are looking to recruit a creative director to sit in our consumer PR team."
Good Relations was incorporated into VCCP Partnership in 2015 after the brands' parent company Chime was acquired by a private equity-led consortium. Good Relations was listed at number 48 on PRWeek’s most recent UK Top 150 Consultancies report, with revenue of £6.4m in 2016.