A review of existing cases against new risk criteria reduced case volumes from 900 in July 2014 to 371 by the end of the year, chief executive Lesley Titcomb said in her introduction to the Pensions Regulator annual report.
"This means we are well placed to be able to manage rising volumes of detailed high-risk casework," she said.
While the number of cases has reduced, the complexity and time commitment of new cases has increased, she said.
Examples include settlements of £8 million in MG Rover, £184mn in Lehman Brothers and £8.5mn in Carrington Wire, Titcomb said.
"These cases included the successful extra-territorial use of our anti-avoidance powers. We also took successful action in the High Court to prevent further proliferation of a pension 'liberation' model. Along with our government partners there is much to be done to protect members from becoming victims of these arrangements," she said.
The level of legislative change over the past year "cannot be underestimated", Titcomb said.
The revision and launch of the new codes of practice for defined benefit and public service schemes, along with changes to defined benefit schemes, have also taken up much staff time, she said.
Automatic enrolment of employees on to pension schemes has seen 99% of eligible jobholders moved onto qualifying schemes, Titcomb said.
Chairman Mark Boyle said the Pensions Regulator has also been taking an active role in industry efforts to limit pension scams through education and "emergency actions".
"The multi-agency roles that we have undertaken in relation to scams is an example of the increasingly prominent role we are playing in the in the national conversation around retirement savings," Boyle said.
The report also shows the Pensions Regulator received 49 new complaints in 2014-15, compared to 16 in 2013-14. By the end of March this year, eight of the 49 complaints remained in progress.
Complaints were about customer service received, incorrect information or operational processes, the report said.
"This remains a small proportion of those in contact with us, particularly in the context of the major expansion during the year in the number of our stakeholders that have automatic enrolment duties, for example," the report said. 771,518 letters were sent to employers during the year, the report said.