BlackRock has won the mandate to manage £30bn of Scottish Widows assets and invest them.
The Lloyds Banking Group decision comes after the bank said earlier this year it was terminating £109bn of asset management agreements with Standard Life Aberdeen (SLA).
Lloyds said the merger of SLA and Aberdeen Asset Management made the company a competitor, although SLA is challenging this view.
Scottish Widows chief Antonio Lorenzo said BlackRock haD been chosen because "it clearly demonstrated its global market leading capabilities and deep expertise in the UK market".
Another £80bn of assets are still under review.