Weir, who was head of European asset-backed financing and trading at Goldman Sachs, will start at Barclays in November.
He also previously worked at Morgan Stanley, where he was responsible for European commercial real estate lending, and Credit Suisse.
Weir will be reporting to Art Mbanefo, who became head of the financing resource management team in April this year.
The department was set up by Tim Throsby shortly after he became president of Barclays International and chief executive of the corporate and investment bank in December 2016.
As part of a reinvestment push within Barclays International, Weir is the latest in a long line of high-profile appointments, with more expected the coming months.
In addition to Weir, Stephen Dainton was recently made head of equities and Michael Lublinsky is head of macro.