Kaepernick garnered controversy in 2016 as the first NFL player to kneel during the national anthem before games to protest police brutality.
Some on the right have criticized Kaepernick for his actions, with President Donald Trump saying that players who kneel during the anthem should be fired.
Brady has long been friendly with Trump but has opposed the president's condemnation of the protests.
Tom Brady, the New England Patriots quarterback who has maintained a friendly relationship with President Donald Trump, is signaling support for Colin Kaepernick following a controversial Nike ad.
On Monday, Kaepernick shared an image of his face on Twitter with the words "Believe in something. Even if it means sacrificing everything." Nike retweeted the image, which reportedly kicks off a new multiyear deal between the former NFL player and the sportswear company.
The ad quickly sparked controversy. Kaepernick was the first NFL player to kneel during the national anthem before games in 2016 to protest racial inequality and police brutality, which has led to some accusing him and other players who followed in his footsteps of disrespecting the American flag and the military.
However, on Tuesday, Kaepernick received support from an unexpected source: Tom Brady.
Brady "liked" a number of Instagram posts of the Nike ad featuring Kaepernick. According to TMZ, the NFL star liked posts from accounts including LeBron James, Chris Paul, Kevin Durant and GQ, which praised the deal on social media.
A representative for the quarterback did not immediately respond to Business Insider's request for comment.
Brady's social-media support of Kaepernick is especially noteworthy due to his relationship with Trump. The pair have been friendly since the early 2000s, with Trump once reportedly trying to set Brady up with his eldest daughter, Ivanka. Brady even had a "Make America Great Again" hat in his locker in 2015.
In 2017, Brady spoke out against Trump's condemnation of players kneeling during the national anthem as part of a protest against police brutality.
"I respect why people are doing what they are doing," Brady told Oprah Winfrey in an interview this June. "And they’re doing it for different reasons, and that's okay. You know, you can do things for your reason. They can do things for their reason, and you have respect for that. But, I thought it was great."