The former Australia vice-captain has been charged with devising the plot which saw Cameron Bancroft rough the ball with sandpaper at the Cape Town Test.
He, along with captain Steve Smith, have been banned from international and domestic cricket for 12 months, while Bancroft was also sanctioned for his role by Cricket Australia.
Posting on Twitter, Warner said: “Mistakes have been made which have damaged cricket.
“I apologise for my part and take responsibility for it.
“I understand the distress this has caused the sport and its fans.
“It’s a stain on the game we all love and I have loved since I was a boy.”
It comes as former captain Smith is due to face the media in Sydney after being sent home from South Africa in disgrace.
The fallout from the scandal continues, with wealth management company Magellan pulling out of a sponsorship deal with Cricket Australia, while Asics also announced it had terminated sponsorship contracts with Warner and Bancroft.
Hamish Douglass, chief executive of Magellan, said: “Regrettably, these recent events are so inconsistent with our values that we are left with no option but to terminate our ongoing partnership with Cricket Australia.
“We were delighted with the recent Magellan Ashes Series sponsorship and it is with a heavy heart that we have to end our partnership in these circumstances.”
England captain Joe Root said the bans handed to Smith, Warner and Bancroft were a “statement to world cricket”.
He said: “I think it just shows that everyone watching the game, and anyone who supports cricket, supports how they want to see the game played.
“In terms of the bans, that’s a decision Cricket Australia had to make - and that’s for them to decide.
“But the point is they’ve put a statement out there not just for Cricket Australia but for world cricket - and the reaction (to that) is all to do with how people want to watch cricket.”
Smith, captain of the Baggy Greens since 2015, spoke of a “leadership group” making the decision to tamper with the ball.
In announcing the severe punishments, CA revealed Warner, 31, had been charged with devising the plan, instructing a junior player - Bancroft - to carry it out and even demonstrating how to do it.
Warner and Smith had already stepped down from their roles as captains for the Sunrisers Hyderabad and Rajasthan Royals, respectively, before their punishment was announced, and the IPL has since confirmed both men would be banned “with immediate effect from participation” in the lucrative Twenty20 tournament this year.
All three players, sent home from South Africa, will be permitted to play club cricket to maintain links with the cricket community.