In a statement for PRWeek, a spokesperson for Jowell emphasised that her role at Chime would not be a distraction in her bid to become Labour's mayoral candidate.
"Her contract with Chime is paid employment on a very limited and part-time basis," the spokesperson said. "She is absolutely focused on the campaign to be Labour's candidate for the London mayoralty, and on delivering the change that London needs."
Chime said Jowell, who stepped down as an MP this year, will not be asked to undertake any advocacy that has any bearing with her role in Government or as a parliamentarian to any of the group’s contacts.
"The role as executive chairman of the Chime Specialist Group will be entirely separate of any activity relating to the Mayor of London 2016 candidacy," the company stated.
Jowell was culture secretary 10 years ago when London was awarded the 2012 Olympics. Another prominent figure involved in that bid, Lord Coe, was also recruited by Chime in early 2013 to be chairman of its sports marketing consultancy CSM. Meanwhile, 2012 Olympics comms chief Jackie Brock-Doyle is currently chair of the Chime-owned PR agency Good Relations.
Jowell held the seat of Dulwich and West Norwood between 1992 and 2015.
Chime said Jowell’s role would focus on developing thinking across the group in two distinct areas: social purpose, or how brands, communities and government can collaborate to achieve a new shared, common purpose that builds resilience into business and society; and innovation, with a focus on social enterprise, digital inclusion and acceleration.
Chime Specialist Group includes PR agencies Teamspirit, Harvard and inEvidence.
Jowell said: "I am delighted to take up this newly created role and work with consultants and communications experts who share my view that the greatest opportunities exist where businesses create reciprocal benefit for customers and the communities in which they operate. Being able to partner with organisations passionate about their role in our wider society and be a part of the dialogue on future innovation is an opportunity to be relished."
Jo Parker, CEO of the Chime Specialist Group, said: "We are honoured to have Dame Tessa join us at an exciting time of growth for the group. Our model brings together specialists in consultancy and communications across a range of sectors, and I know that the exceptional experience and insight of Dame Tessa will inspire the next stage of our expansion. We look forward to working with her."
This article was updated on Monday afternoon with a comment from Jowell's spokesperson.