Wildman will be replaced by UK sales director Stuart Flint, who takes the role of country commercial director and managing director for Yahoo in the UK.
His exit is believed to come amid a restructure across Yahoo's regional operations, being led by Dawn Airey, who joined the company as senior vice president of operations in Europe, the Middle East and Africa last summer.
Based in Yahoo!’s Central London office, Airey is now believed to be in the process of creating a number of senior roles across the region.
A Yahoo spokesperson declined to comment on the restructure, but said: "We want to take the opportunity and thank James for his leadership and strong contribution over the years and wish him all the very best with his new endeavours."
Wildman joined Yahoo in 2010 from Virgin Media sales house IDS, prior to which he held senior sales and management roles at GMTV and Universal Studios Networks.
Yahoo relocates to Ireland
Yesterday, in a move likely catch the attention of Her Majesty's Revenue and Customs, Yahoo contacted UK customers to inform them the company plans to reorganise its European operations from a single European entity based in Ireland from March.
In a statement, Yahoo said of the changes: "As we have stated in the past, the structure of our business is driven by business needs and we believe it is in the best interest of our users to have Yahoo EMEA provide all services for all users in the region.
"There are a number of factors which influence such business decisions from our perspective: Ireland has an extensive data centre infrastructure that helps us serve our EMEA users in the most efficient way.
"In respect of Ireland in particular, Dublin is already the European home to many of the world’s leading global technology brands and has been a home for Yahoo for over a decade."