"It's a fantastic opportunity," said the England striker, who will leave Tottenham Hotspur for Canada at the end of February. "I'm excited like a little kid.
"It's always a challenge when you go to a new club, play new competition. That's what I play football for and I'm going to enjoy it. I'm looking forward to it."
Defoe and Bradley will be charged with sparking a squad that has never managed a winning season or a play-off berth in its seven-season history.
"For this moment, I couldn't be in a better place," said the USA midfielder, who moves from Roma. "I've never been more excited and more motivated for any challenge in my career. What they are trying to build here is really special."
Defoe added: "I'm looking forward to putting my boots on and scoring goals, showing people why I'm a good signing. All you want to do is get out there and let your football do the talking."
And the 31-year-old is not giving up on making Roy Hodgson's squad for the 2014 FIFA World Cup Brazil™. "If selected, I'll be ready," insisted Defoe.
The move to Toronto should ensure abundant playing time for both, helping their World Cup preparation.
Add the signings of Canadian international Dwayne De Rosario and Brazilian striker Gilberto and Toronto could go from six wins and 11 draws in 34 matches last year to the team to beat in 2014.
Bright prospects for TFC and the MLS
"Why can't we be great?" asked club owners Maple Leaf Sports and Entertainment chief executive Tim Leiweke. "We didn't win anything today, but we created a great opportunity."
Leiweke was working for the owners of the Los Angeles Galaxy when English star midfielder David Beckham signed with the club in 2007 from Real Madrid, a move that helped lift the North American league's profile worldwide as well as with American and Canadian fans.
Beckham's star power ensured he would be a top attraction for international matches as well as in MLS games, but Defoe and Bradley are more aimed at raising the level of talent in MLS and showing the willingness to spend to do so.
"We had a number of goals that included building this club with a vision for contending for playoffs and championships while also being recognised and competitive internationally," said Toronto FC general manager Tim Bezbatchenko. "Adding star players like Jermain and Michael will help us a great deal in reaching those goals."