Hamilton, the only black driver in the sport, wore a Black Lives Matter t-shirt, while other drivers, who all lined up with him at the front of the grid, sported black tops saying “End racism”.
However, six of the 20 drivers remained standing during the protest before the Austrian national anthem.
Ferrari’s Charles Leclerc and Red Bull’s Max Verstappen had confirmed a split among drivers when they said they would not take a knee.
They were joined by Carlos Sainz of McLaren, Danil Kvyat of Alpha Tauri, Antonio Giovinazzi and his Alfa Romeo team-mate, former world champion Kimi Raikkonen.
“Today was an important day for me and all the people out there who are working for and hoping for change, for a more equal and just society,” Hamilton wrote on Instagram after the race in which he finished fourth.
“I may get criticism in the media and elsewhere, but this fight is about equality, not politics or promotion.
“To me it was an emotional and poignant chapter in the progress of making F1 a more diverse and inclusive sport.”
It’s understood that Hamilton had irritated some of his rivals by suggesting they “lacked understanding” of the issues.
Hamilton had explained his views to his fellow drivers before the race, claiming that silence is “generally complicit”.
“No-one is perfect but if we all chip in and do our part, we can see change. I truly believe that,” the 35-year-old added in his Instagram post.
In a statement on Twitter before the race, Leclerc said: “All 20 drivers stand united with their teams against racism and prejudice, at the same time embracing the principles of diversity, equality and inclusion, supporting F1’s and FIA’s commitment.
“I believe that what matters are facts and behaviours in our daily life rather than formal gestures that could be seen as controversial in some countries.
“I will not take the knee but this does not mean at all that I am less committed than others in the fight against racism.”
Verstappen tweeted: “I am very committed to equality and the fight against racism.
“But I believe everyone has the right to express themselves at a time and in a way that suits them. I will not take the knee today but respect and support the personal choices every driver makes.”
The Grand Prix Drivers Association (GPDA) had issued a statement on Saturday claiming the drivers were united in opposing racism, but supporting each individual in being free to choose how to express their positions.
Jean Todt, president of Formula One’s ruling body, FIA, told reporters at Spielberg, however, sport should be wary of allowing itself to be used by political influences.
“Sometimes there is a tendency to use it as a weapon and we have to be very careful of that, but I admire people who have conviction and do as much as they can,” he said.
The debate over taking a knee came as FIA pledged to give one million euros ($1.1m) to the sport’s new ‘We Race As One’ diversity foundation.