The US energy provider to 1.2 million electric and 127,000 natural gas customers in Missouri has filed a proposal with the Missouri Public Service Commission to reduce bills for all its customers.
If approved, the 6% decrease will be the utility's second since last summer.
The proposal is part of the utility's Smart Energy Plan, to keep consumer energy bills stable and predictable.
The utility's consumer bills are 21% lower than the national average. The reduction is expected to come into effect in May 2020.
Ameren Missouri is planning to invest $5.3 billion to modernise its grid by implementing more than 2,000 projects over the next five years.
$1 billion will be directed towards expanding the portfolio of wind energy to reduce carbon emissions.
Ameren has set a goal to reduce emissions by 80% by 2050, from 2005 levels. The company also plans to roll out the first of its new generation of smart meters starting in 2020.
Michael Moehn, chairman and president of Ameren Missouri, said: "These investments are providing real value for our customers, creating an energy grid that is more reliable and more resilient to severe weather. These upgrades also allow for the integration of more solar and wind energy as we transition to cleaner energy."
"We continue to offer new products and services for our customers, such as a recently launched mobile-friendly website, new proposed specialized rate options and paperless billing incentives," said Tara Oglesby, vice president, customer experience, Ameren Missouri. "These new offerings, combined with the Smart Energy Plan and the largest energy efficiency plan in our company's history, provide our customers with more ways to manage and reduce their energy usage for many years."