Permira is to combine the business with London-based Bestinvest, which has extensive execution-only activities, and was bought from 3i last year.
The move affects 50 staffers in Tilney's Edinburgh and Glasgow offices, and those based in Liverpool and Birmingham.
Permira partner Philip Muelder said: "The UK wealth management industry has strong growth characteristics but is currently very fragmented.
"In combining Tilney and Bestinvest, we will bring together two highly regarded firms to create a truly market leading, UK-wide wealth manager."
The Tilney name will be used for its discretionary management activities.