His confirmation as the executive creative director follows a three-month trial, during which Morris took on extra departmental responsibilities after Lowe's split with Damon Collins.
The promotion for Morris, 36, an art director, comes 22 months after he joined the agency. During his 13-year career, he has been associated with a string of award-winning work.
Morris takes charge of 17 teams as Lowe, under its chief executive, Matthew Bull, attempts to get itself back on course after a string of account losses, staff redundancies and a restructuring.
Bull said: "I think our work has been good but it still has to step up markedly. We have some terrific opportunities but we have to take our creativity into a different league. I don't want there to be any such thing as a 'typical' Lowe ad."
Morris is best known for the partnership he formed with the copywriter James Sinclair, now the creative director of the independent agency See.
It began at the then Miller & Leeves and continued at Bainsfair Sharkey Trott where it survived three mergers - with BDDP, GGT and, finally, TBWA Simons Palmer.
The team's reputation was built on the acclaimed "double life" commercial for Sony PlayStation, which it produced at TBWA\London.
They were also behind Bartle Bogle Hegarty's "keep walking" campaign for Johnnie Walker whisky and BMP DDB's "lost dog" work for Volkswagen.
Bull added: "Ed not only has great vision but understands that great vision also requires action. He has also done terrific work which has earned him the respect of the department."
Morris said: "The agency has been through a lot since its merger with Lintas but I think we'll win the fight. On the inside we know how good it is."
Morris insisted that Bull, himself a former creative, would give him free rein. "Matthew has forthright opinions - but not as forthright as mine."