Jenkins, formerly a creative director of WPP agency The Partners, will be responsible for design execution and visual expression.
She will work directly with Added Value's in-house design studio and audio-visual production team to champion the use of design and interactive media.
During her career Jenkins has worked on brands including Wedgwood, Vertu, Models 1, Smirnoff and BBC iPlayer.
Pugh, who joined Added Value in 2000, has been promoted to creative director with responsibility for strategy.
Her new role will be to evolve and create bespoke marketing and insight tools to benefit Added Value's clients.
Pugh will continue to work closely with Added Value's cultural insight team to support its growth.
She previously worked on the development of The Archetype Game, a board game that claims to enable marketers and brand managers to "decode and define brand character, and inform the development and activation of brand positioning".
The game was initially developed for Vodafone as part of a wider programme to align the brands of the mobile network's overseas acquisitions with its global brand.
Bart Michels, managing director of Added Value, said: "We believe the combined creative talents of Nina and Izzy will further put creativity at the heart of what we do, giving our clients solutions with more impact, relevance and, most importantly, more value."
Added Value is part of Kantar Group, the information, insight and consultancy arm of WPP.