Mercedes has retained the black-based livery for this year following its switch before the start of last season in a strong anti-racism message as supported by Lewis Hamilton.
But the team has replaced the speckled-star design on the engine cover, in favour of a series of stickers for its AMG brand against a background that fades to silver.
Although there is a majority carry-over from the W11 following the freeze on development, all Formula 1 teams have been permitted to spend two development tokens on major updates for the 2021 cars.
Mercedes revealed in February that it was battling some “issues” with its updated power unit, but was confident of getting fixes in place in time for the new season.
The team announced shortly after the end of the season that INEOS had become a new shareholder, taking a one-third share in the squad, with team principal Toto Wolff upping his stake to the same level.
Wolff also agreed to continue to serve as Mercedes team principal for at least three more years, having overseen its streak of seven consecutive title wins since 2014.
The deal ensured Hamilton stayed on the grid, but the short deal has led to a number of questions about his future beyond 2021.
Hamilton will be joined at Mercedes for a fifth season by championship runner-up Valtteri Bottas, who is also out of contract at the end of the year, making the team a key focus point in the driver market.
The Mercedes W12 will enjoy its first extended on-track running at the start of pre-season testing in Bahrain, which takes place from 12-14 March.