Lowery was a boyhood Sunderland fan who sadly lost his life to a rare form of cancer in 2017 at the age of just six.
Defoe had a special bond with the youngster, who was a mascot for the Black Cats, and even walked out alongside him at Wembley for England in his final months.
Since his passing, The Bradley Lowery Foundation has been set up, and now an initiative called Super Brad's Pad, a luxury holiday home for families with poorly children.
Aiding the process has been Bayern Munich's Kane, who has donated a 24 carat gold football signed by the England team, along with signed England and Bayern shirts.
Discussing the foundation, Defoe said: "Bradley was one of the most inspirational children this world has ever seen, and he will never stop inspiring us. Brad was my best mate and I will never stop raising money in his name.
"After the incident, it has been amazing seeing so many people unite from so many different football clubs, so many different walks of life, to raise money for the Bradley Lowery Foundation.
"I'm so sorry for what Gemma and Carl had to experience, but we want to try and make positive change moving forward. The fundraiser that the Sheffield Wednesday fans set up was incredible and we want to keep raising money to help."
Defoe then went on to praise his former Spurs teammate, adding: "You all know what an amazing footballer Harry Kane is, but what you don't know is that he is an even better person.
"Harry has the biggest heart and has donated to help raise money for the Bradley Lowery Foundation. I've known Harry for a long time, and I'm not at all surprised that he's offered to help donate and raise funds.
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"He's a leader on the pitch, he's the kindest person that you'll meet off it. As the captain of England, he is the perfect role model of what every kid should look up to in how he conducts himself both on and off the pitch. I'm beyond lucky to know Harry and call him a mate."
Bradley's mum Gemma Lowery added: "This last week, we have seen the whole football community come together and it has been amazing what you can achieve with so many kind people out there. This is the power of the football family.
"We even have Harry Kane supporting the Bradley Lowery Foundation, which is unbelievable. Having the England Captain support the Foundation would mean the world to Bradley as he was such a big fan of the England team. Getting to walk out as the mascot with Jermain and the England team at Wembley meant the world to him, and I know Harry's donations would too.
"It just shows the power of football as a sport, how the biggest names in football come together for good. This is what football is all about."