In February 2014, Duke Energy polluted the Dan River in Eden, North Carolina with 39,000 tons of coal ash and 27 million gallons of wastewater. The spill happened after Duke refused to supply the Dan River Steam Station with $20,000 to inspect four pipes, including the one that collapsed. In addition to civil penalties levied against the company, Duke plead guilty to nine counts of criminal negligence under the Clean Water Act, resulting in a $68 million fine and a mandate to spend $34 million on conservation efforts in North Carolina and Virginia. Duke's carelessness endangered both local wildlife and thousands of North Carolina residents who relied on the Dan River for drinking water and recreation.

In 2013, Duke Energy Renewables Inc. was fined $1 million and sentenced to five years of probation for failing to prevent the deaths of migratory birds at a wind turbine site in Wyoming, despite being warned of the issue by the US Fish and Wildlife Service. In total, 14 golden eagles and 149 other protected bird species were killed. 

Other sanctions against Duke include $1.1 million in criminal penalties for an oil spill in Ohio in 2016, $25.1 million in fines for groundwater contamination in North Carolina, $93 million in fines and restitutions to resolve Clean Air Act violations in Indiana, and a $1.7 million settlement for a fire that burned 2,300 acres of Cherokee Nation forest lands. 

In 2016, Duke Energy paid over $80 million to settle a lawsuit alleging that they created a fraudulent subsidiary to funnel tens of millions of dollars of illegal rebates to corporate customers to avoid opposition to rate hikes.

During California's Energy Crisis of 2000-2001, Duke allegedly overcharged customers for wholesale electricity, for which it paid a $207.5 million settlement in 2004. 

In 2017, Duke paid $9.4 million to settle their part in an alleged conspiracy to raise the price of natural gas in Kansas, Missouri, Wisconsin and Colorado.

In November 2010, an apartment in Lebanon, Ohio exploded after a Duke Energy contractor failed to follow basic protocol when reconnecting gas service. The explosion resulted in an estimated $1 million in property damages and seven injuries. One of the occupants of the apartment received burns to 15 percent of her body; the other had second degree burns to her hands and face. The investigation also found that Duke's own established procedures and oversight of contractors did not meet basic safety guidelines. In 2012, Duke Energy paid $500,000 in fines for this incident.