The disclosure in the bank's financial results comes weeks before a possible no-deal Brexit and adds to warnings about the potential fall-out for the economy from other lenders.
Barclays said pre-tax profits for 2018 fell 1% to £3.49bn as it counted the cost of past misconduct including a £1.4bn settlement with US authorities over the sale of toxic mortgage assets in the run-up to the financial crisis.
Stripping out these litigation and conduct costs, earnings rose by 20% to £5.7bn.
"In the course of the year, having resolved major legacy issues... we started to see the earnings potential of the bank."
The results come as the bank faces sustained pressure from activist investor Edward Bramson for a shake-up.
The provision made by Barclays reflects an expected impact of uncertainty on its UK credit card and corporate loans operations.
Barclays said 2018 profits for its ring-fenced UK consumer business were up by 12% to £1.96bn, though for the fourth quarter they were 14% lower at £390m compared to the same period a year ago.
The bank said it saw "continued momentum" in mortgage lending and customer deposits but saw profit margins on its loans squeezed - amid what other lenders have said is a tough competitive environment.
Profits at the lender's international arm also rose, including a 26% rise in earnings for its corporate and investment bank to £2.59bn.
The bank disclosed that Mr Staley was paid £3.4m in 2018, down from £3.9m in 2017 after seeing £500,000 of previous bonuses clawed back following an investigation into his attempt to uncover a whistleblower.