The launch, which is scheduled for 5 April, will combine the direct mail campaign with a television one under the strapline 'Our Power is our Number'.
It will be supported within the charity's shops with new signage and interiors, as well as further DM pieces over the next few months.
The C5-sized direct mail pack, which was managed by Kitcatt Nohr Alexander Shaw, includes a 16-page booklet detailing Age UK's remit and how to use or get involved with the charity.
Age UK marketing director Lisa McCormack said: "We need to raise awareness of our services and commercial products to provide better support to people in later life. We believe that the activity we're putting in place will help us achieve our goals and ultimately deliver our promise to our audience."
Age UK launch involves DM piece sent to 2.5m
Age UK is to launch as the new organisation combining Help the Aged and Age Concern with a direct mail pack sent to 2.5m people.