Model Munroe Bergdorf has rejoined L'Oreal Paris after she was sacked by the brand in 2017 for posting about "the racial violence of white people".
Last week, she criticised L'Oreal after it posted a support message for Black Lives Matter, saying the brand "threw me to the wolves" when it fired her.
Bergdorf said the brand's new president Delphine Viguier had apologised for the way the situation was handled.
She will now join the company's UK diversity and inclusion advisory board.
On 1 June, the transgender model and activist tweeted: "You dropped me from a campaign in 2017 and threw me to the wolves for speaking out about racism and white supremacy. With no duty of care, without a second thought.
"I had to fend for myself being torn apart by the world's press because YOU didn't want to talk about racism. You do NOT get to do this. This is NOT okay, not even in the slightest."
After speaking to Viguier, she wrote that she believes in "accountability and progress, not cancellation and grudges".
She said: "While what happened three years ago was extremely traumatic for me personally and professionally, sitting on a board to provide a voice and a champion for black, trans and queer voices in the beauty industry is important for me.
"It feels good to finally have closure on this matter and I look forward to new beginnings with the L'Oreal team."
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On L'Oreal Paris's Instagram page, Viguier said she had had "an honest, transparent and vulnerable conversation" with Bergdorf.
"Here is what I heard from her: Three years ago, Munroe felt silenced by a brand, L'Oreal Paris, that had the power to amplify her voice.
"While we both agree today that negative labels should not be used to define all individuals in any group, I understand much better the pain and trauma that were behind Munroe's words back then and the urgency she felt to speak in defence of the black community against systemic racism.
"I regret the lack of dialogue and support the company showed Munroe around the time of the termination. We should have also done more to create a conversation for change as we are now doing.
"We support Munroe's fight against systemic racism and as a company we are committed to work to dismantle such systems."
Viguier said L'Oreal would also donate to causes that support social justice.