BASEL, Switzerland—The world’s largest banks will have to hold 16-20% of their risk-weighted assets in equity and cancelable debt to shield taxpayers from big bills for bailing out failed banks during a crisis, according to a plan by global regulators published Monday.

The plan, drawn up by the Basel-based Financial Stability Board, would force the biggest lenders to maintain a sizable capital cushion so that they could be wound down without causing global financial panic. Banks are considered to be systemic if they pose a...