The 17-year-old will be looking for first-team experience with the O's after signing his first professional contract at White Hart Lane in July 2010.
Kane scored 18 times in 22 games for Spurs under-18's last season and his form even earned him a place on the first-team bench during the campaign.
Orient boss Russell Slade told the club's official website: "We're really happy that Harry has joined us on loan.
"He is a player that we've watched several times and I'm sure he will have an impact with us over the coming months."
Source: PA
Source: PA