In her new post, Warder will take responsibility for all UK creative work and a new planning team. She will remain MD of the agency's consumer shop JCPR.
Bigg will take on responsibility for corporate, financial and public affairs in addition to his role as European practice chair, corporate.
They will also join the company’s new operating committee alongside CEO Ed Williams; COO Steve Spurr; CFO Claire Dobson and HR director Rebecca Hall.
Williams said: ‘Both Ruth and Alex’s new roles will see them work across all of the Edelman teams, ensuring that we continue to offer integrated, groundbreaking and creative thinking for all our clients. Ruth’s role in particular will ensure that we continue to provide our best and most innovative work.’
Alongside the new operating committee, an executive management team has also been created.
This comprises MDs Jamie Lundie, who now takes on day-to-day responsibility for the corporate and financial practice; Leah Katz (digital); Rishi Bhattacharya (energy and industrials); Chris Rumfitt (public affairs); Matt Hurst (technology) and new hire Paul Gittins (health).
There will also be three other additions to the new management team.
Nick Barron takes on the role of executive director, business development, with a remit of developing a UK-wide strategy for new business.
Sharon Reid is promoted to executive director, creative, with oversight of planning and strategy as well as creative vision and creative newsroom, and Jo Sheldon will become executive director, media strategy.