Ellis, who has 27 England caps, was among the 37-man squad announced at a press conference on Tuesday lunchtime.
Seven other Englishmen are included in a squad which will be captained by Munster and Ireland second row Paul O'Connell.
The announcement was made in London by tour manager Gerald Davies and head coach Ian McGeechan.
" Being selected as a Lion is a huge honour for a player and marks a major highlight in his career. I congratulate each of the players on their selection and look forward to a successful and rewarding tour,” said Davies.
"As ambassadors for British and Irish rugby, I know the players will be dedicated to the adventure and task ahead. They might hail from four different countries but on tour they will play for the one jersey, one philosophy, one style and have one ambition, to return home as winners."
Head coach McGeechan said, "To get where we are today and the announcement of the 37 players has taken a lot of thought and work. Over the last six months the Lions coaching staff has attended countless matches, analysed endless games and taken the counsel of national and domestic coaches. Today marks the end of a comprehensive and detailed selection process.
"Naturally there were some tough decisions and there will be disappointed players, but I am confident that this is a very strong and capable squad. Its composition reflects the form shown in the 6 Nations and domestic rugby, and has a balanced blend of experience and youth."
2009 British & Irish Lions squad
Full-back
Lee Byrne (Wales)
Rob Kearney (Ireland)
Wing
Shane Williams (Wales)
Leigh Halfpenny (Wales)
Ugo Moyne (England)
Luke Fitzgerald (Ireland)
Tommy Bowe (Ireland)
Centre
Tom Shanklin (Wales)
Jamie Roberts (Wales)
Brian O'Driscoll (Ireland)
Keith Earls (Ireland)
Riki Flutey (England)
Fly-half
Ronan O'Gara (Ireland)
Stephen Jones (Wales)
Scrum-half
Mike Phillips (Wales)
Harry Ellis (England)
Tomas O'Leary (Ireland)
Prop
Gethin Jenkins (Wales)
Adam Jones (Wales)
Andrew Sheridan (England)
Phil Vickery (England)
Euan Murray (Scotland)
Hooker
Jerry Flannery (Ireland)
Lee Mears (England)
Matthew Rees (Wales)
Lock
Alun-Wyn Jones (Wales)
Paul O'Connell (Ireland)
Donncha O'Callaghan (Ireland)
Simon Shaw (England)
Nathan Hines (Scotland)
Flanker
David Wallace (Ireland)
Stephen Ferris (Ireland)
Alan Quinlan (Ireland)
Joe Worsley (England)
Martyn Williams (Wales)
No8
Jamie Heaslip (Ireland)
Andy Powell (Wales)
