Fletcher is taking up the role at the rugby governing body this week.
He will report to the RFU's chief commercial officer Sophie Goldschmidt.
His appointment means there will be a minor internal restructure at the RFU's marketing function. Barry O'Hearn will take on more responsibility for events and tournament marketing, whereas he previously had a more general marketing role.
Fletcher was most recently at O2, where he spent five years as head of sponsorship.
During his tenure there, he headed up a number of campaigns, including the 2007 'Never Surrender' and 'O2 on the Beach' campaigns.
Aside from his experience at O2, Fletcher spent four years at the Australian Rugby Union, and has also worked at the marketing agency, Momentum.
At the RFU, Fletcher will work closely with Goldschmidt, particularly in overseeing the RFU's internal marketing function and will work on brand development, rugby and event promotion, fan clubs and creative design.
Follow John Reynolds on Twitter @johnreynolds10