Aid organisations have reported 80 cases where workers have harmed people, or put them at risk, international development secretary Penny Mordaunt has said.
Reports of children being sexually abused are among the current and historical cases referred to the Charity Commission since 12 February.
Last month it emerged that former Oxfam workers paid for sex while in Haiti.
It was a "wake up call" for the sector, Ms Mordaunt told a safeguarding summit.
The cases span 26 charities and groups - seven of which were reporting cases that had occurred in the last financial year - and cover the "full spectrum" of safeguarding incidents, she added.
The charities involved in the cases have not been named.
The reports come after Ms Mordaunt wrote to 179 British charities and agencies asking them to report any cases of abuse to the Charity Commission, in the wake of the sex exploitation scandal which has engulfed the sector.
Aid charities had to be honest about their past mistakes in order to win back the trust of the British public, she said on Monday.
Her message to those who sought to exploit the aid sector was: "We will find you. We will bring you to justice. Your time is up."
The cabinet minister said government funds would not be approved unless organisations passed "tough new standards" set by the Department for International Development.
These standards - she said - would be "world-leading" and "exacting" and have now come into force.
Attendees at the London event have been asked to find a way "staff can be properly vetted and monitored as they move between organisations and countries" and come up with measures to support and protect whistleblowers and survivors of exploitation or abuse.
NGOs and charities at the summit will sign a joint statement setting out the key principles they will adhere to and agree a set of practical actions to improve standards.
The Charity Commission said it would work with organisations to make changes and chairwoman Baroness Stowell said she was encouraged to see "a firm commitment to bringing about cultural change in charities".
"But however noble the cause, it will never justify means which fall below basic standards of conduct expected of any organisation," she added. "And if we are to restore public trust and the nation's pride in what charities achieve, we have to show that's what we understand."