The move comes one year after the duo were elevated to lead the EMEA business.
Owner Huntsworth said it follows a "strong year for Grayling... in spite of the challenges created by the pandemic".
The global CEO role has not existed at Grayling since 2015, following the departure of Pete Pedersen.
Huntsworth, which went private earlier this year with its sale to private equity firm CD&R, said having worldwide leadership "will allow the agency to continue to deliver even greater integration, not just between offices but also between practices and shared services, in line with client needs and expectation".
The firm continued: "The positive momentum set by Grayling in the UK & Europe under Scholefield & Jukes’s leadership and the addition of key talent creates a perfect springboard to extend this approach and success further afield."
Neil Jones, CEO of Constellation - Huntsworth's comms division - said: “Sarah and Richard have consistently proven their ability to drive significant growth, even in the most challenging of circumstances. That growth has been driven by an enhanced roster of services and people, and we are now seeing increased client opportunities as a result. By bringing Grayling worldwide under single leadership, it allows us to utilise our shared resources across all territories and service more global clients.”
Scholefield said: “Our collaborative approach between the UK & Europe has already paid dividends, and proved that when we work closely together, we are more successful and can drive even greater value to our clients. As we continue to evolve our Grayling proposition, we will work together under a shared culture and with a single creative and strategic approach, using our shared resource and momentum to the benefit of all our Grayling clients and staff worldwide.”
The promotions follow a period when the agency has been expanding its senior team in the UK and EMEA.
In January, Grayling announced it had promoted Jonathan Curtis to MD and expanded Tom Nutt and Nathan Kemp's roles to head of corporate and head of creative and planning, respectively, across the UK and Europe. The following month it announced the appointment of Peter Murray from Cicero as head of corporate affairs.
Last autumn Grayling launched a creative services division, IGNITE, and hired creative director Julian Cirrone from M&C Saatchi PR.
Revenue in Grayling's UK business rose 19 per cent in 2019 to £12.5m, according to PRWeek estimates. That compares to an estimated eight per cent growth globally - overall revenue in 2019 reached an estimated $41m.