Dee, who is the COO of the Red Sox, will make his transition shortly. The Red Sox said that details of that time-frame will be forthcoming.
In the meantime, Dee was formally introduced to Miami on Sunday.
Boston's ownership has nothing but praise for Dee as he gets ready to embark on the next chapter of his professional life.
"The departure of Mike Dee marks a great loss for the Boston Red Sox and other NESV affiliates," said principal owner John Henry. "His rare combination of imagination and ingenuity has helped this franchise reach historic milestones on and off the field. His work with Fenway Sports Group and Roush Fenway Racing was critical to the growth and success of those entities, and his work with every facet of NESV set high standards of excellence across the board."
Dee has been with the Red Sox since July 15, 2002, and he moved into his current position on March 7, 2004.
The Red Sox have won two World Series championships during his tenure, and he helped maximize the team's ever-growing popularity with creative revenue streams.
"The strength of this organization comes from its people, and the success of the Red Sox demonstrates the impact that a creative individual like Mike Dee can have on a franchise and its fans," said chairman Tom Werner. "Mike played a key leadership role in one of the most productive front-office teams in Major League Baseball. His indefatigable nature ensured that our partners, sponsors and fans always received the highest possible value for their investment in this team."
This was the start of Dee's 15th season in Major League Baseball, but he will now put his skills to use in the NFL.
"Mike and I have enjoyed a deep friendship and built strong professional bonds since we met in Baltimore over 15 years ago, and I will miss him in both capacities," said president/CEO Larry Lucchino. "Mike is a good, fun guy, and our accomplishments in San Diego and Boston are in a major way attributable to his broad talents and dedication.
"He is one of the most creative, versatile and energetic executives in all of sports. The Miami Dolphins could not have selected a better person for the challenges and opportunities that lie ahead of them. For this position, Mike Dee is a bona fide first-round draft pick."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.