Also, for the first time, the agency has opted to appoint creative group heads. Senior writer Oliver Devaris takes up one of the positions, while Paul Dunne is the new creative head, responsible for telecommunications giant Optus.
Welsh's position is in line with that of Melbourne creative director Paul Taylor. Both creative heads answer to M&C Saatchi national creative partner Tom McFarlane.
McFarlane said the creation of the post of Sydney creative director was borne out of long consideration and the role was styled around Welsh's talents.
"In true M&C Saatchi style we have been grooming Ben for this role for a while now," McFarlane said.
"We first met when he was doing Copyschool and it's been fantastic to work with him over so many years."
McFarlane indicated Welsh's appointment was a pre-cursor for a later, international posting.
"He joins home-grown CDs like Paul Taylor in Melbourne, Jason Ross in New Zealand and Matt Eastwood in London who have moved through the ranks of the creative department to become CDs," McFarlane said.
Welsh launched into advertising several years ago through Copyschool.
His first job was with McCann-Erickson in Melbourne and later DDB Melbourne.
Welsh has been with M&C Saatchi for the past six years.
He joined all agencies initially as a writer.
At M&C he will oversee eight creative teams in partnership with senior art director Chris Round, winner of this year's Grand Prix for direct at Cannes.
Welsh has a string of awards under his belt including a Caxton last year for his Audi work, silver and bronze MADC medals and some bronze and finalist gongs from AWARD. Welsh is now co-chairman of AWARD.
Welsh said he appreciated the creative support the new role would give him.
"I'll have a lot of support above and below," Welsh said. "I think by having more of a structure we should be able to devote more time to improving the work.
"When you look at all our clients we've just about picked up something for every client we've got. We don't have one client that delivers all the awards. But what we need to deliver is more consistency."