The charity formed by the merger of Breast Cancer Now and Breast Cancer Care will keep the name Breast Cancer Now.
The two charities completed their merger in April, when they said the move created the UK’s first comprehensive breast cancer charity.
The charities initially kept their own branding and it was expected that they would unveil a new identity within a year of coming together.
But the merged charity said it would be adopting the Breast Cancer Now name with new branding using the colour palettes of the two legacy charities.
The branding has been launched today to tie in with the start of Breast Cancer Awareness Month.
The charity said the incomplete "o" in the logo represented the "coming together of research and care to support those affected" by breast cancer.
An advertising campaign has also been launched across radio, digital channels and on buses and the London Underground.
The advertising campaign was designed by the creative agency Nice and Serious, and the rebrand was completed by the brand agency Wolff Olins.
Breast Cancer Now declined to disclose the cost of the campaign and rebrand, but a spokeswoman said that there was a "strict budget" in place for the project.
The charity employs 334 staff at offices in London, Sheffield, Cardiff, Edinburgh and Glasgow. It said there had been 10 redundancies in total as a result of the merger.
Baroness Delyth Morgan, chief executive of Breast Cancer Now, said: "With our combined knowledge, passion and resource, we hope Breast Cancer Now will be the trusted friend that people affected by breast cancer can turn to for caring support, the expert authority on breast cancer research, making breakthroughs and driving progress, and a determined vehicle for change to make sure anyone affected by breast cancer gets the best possible treatment and care."