Contracts have been exchanged with Australian-owned Computershare, which has an office in Halifax.
Skipton will receive an initial consideration of £47.5m, plus an adjustment for surplus working capital, together with potential additional payments based on revenue growth in 2015 and 2016.
The initial consideration will generate a profit in the order of £26m to be recognised in Skipton’s results in the second half of this year.
Skipton Group chief executive David Cutter said: "HML has been a major success story for Skipton of which we are very proud.
"However, we anticipate major growth opportunities arising in the mortgage outsourcing market which are best seized by the investment from a large multinational company.
"We believe Computershare will be an ideal new owner for HML and I wish all staff at HML the very best for the future."
HML will retain its head office in Skipton.
Skipton was advised by Deloitte and Addleshaw Goddard's Neil Woolhouse and Mark Hallam, Matthew Davies, Chris Dereix, with support from Ian Sampson.
