The 38-year-old will travel to Germany for the duration of the tournament, to provide support for Jordan Pickford, Aaron Ramsdale and former Red Dean Henderson.
An experienced and accomplished professional, Heaton has previously won three senior England caps and will help the current squad in training this summer.
Tom joins a Three Lions squad that includes two of his United team-mates in Luke Shaw and Kobbie Mainoo, with group-stage matches against Serbia, Denmark and Slovenia coming up.
In a statement to announce the news, manager Gareth Southgate said: “I am really pleased Tom has agreed to join us in Germany.