Both players have hit it off in their first full seasons in the Premiership and have England star potential.
18-year-old Lennon has stepped up to the Under 21's since his move to White Hart Lane from Leeds United last summer.
Dawson was already a regular in Peter Taylor's side when he joined Tottenham in a move from Nottingham Forest in January 2005.
Sporting director Damien Comolli said: "It's terrific for the club that these two young English players have contributed to the squad and shown their ability early on. We are delighted they have underlined their commitment to us by further extending their contracts."
Source: Official site