Weston's appointment comes amid a complete restructure of JCDecaux's sales team, led by strategic firm Boston Consulting Group.
The arrival of Weston coincides with the resignation of the former JCDecaux director of national sales, Jamie Lindsay, after more than 13 years' service with the company.
A further six members of sales staff are currently under consultation as part of the same review process.
In his new role, Weston will report to managing director of sales, Spencer Berwin.
Three main agency-facing teams will support the major out-of-home specialist agencies and will be led by business directors who will report directly to Berwin, as will trading director Daemon Brown.
Weston will lead five product teams: roadside, rail, premier, retail and idea (an acronym of innovation, digital and experiential activation), which will each aim to maximise JCDecaux's offering across its different environments.
Berwin admitted the sales division had experienced "a lot of change" since the acquisition, but said they aimed to provide advertisers with "the easiest and most comprehensive structure, which reflects the scale of the business and our new assets".
The Titan Outdoor business was initially run in parallel to the existing JCDecaux businesses, by a separate sales team led by Weston.
JCDecaux has worked with BCG over the past five months and the new structure was finalised following the result of the Network Rail tender and the clearance of the Titan-Decaux merger by the Office of Fair trading.
JCDecaux bought the Titan Outdoor assets after Titan entered administration in January. Since then, Titan Outdoor chief executive Jon Slatkin, managing director Andy Moug and business delivery director Madalyn Roker have left the company.
Titan Outdoor marketing director Steve Cox left JCDecaux in March, but returned last month as marketing director of JCDecaux Airport.