In 1996, Richardson became the first Republican from Paulding County elected to the Georgia House of Representatives since Robert McWhorter in 1870 during Reconstruction.

The March of Dimes recognized him "for providing extraordinary leadership in passing legislation to reduce the number of premature births in Georgia."

As chairman of the SLC, he works with other southern states to foster greater intergovernmental cooperation and communication to address regional issues.

Richardson's accomplishments in the 2007 legislative session include attempting to ensure that PeachCare, the State's health insurance program for children, remains solvent.

[11] The Atlanta Journal-Constitution reported that the Democratic Party of Georgia had filed an ethics complaint about Richardson based on an allegation that Richardson engaged in an "inappropriate" and "personal" relationship with a female lobbyist from Atlanta Gas Light[12] while the company was seeking legislative approval for a $300 million pipeline across the state.

On February 11, 2008, the Atlanta Journal-Constitution reported that "House Speaker Glenn Richardson and his wife filed for divorce, completed the dissolution of their marriage and got court records of the proceedings sealed – .

[16] The handling of the divorce raised questions as to whether the speaker of the state House received preferential treatment from Judge James Osborne, who was not initially assigned the case but signed the order placing it under wraps.

First Amendment advocates note there is a strong presumption to access to proceedings and records to ensure courts are treating both parties to a dispute fairly.

(Atlanta Journal-Constitution July 13, 2008) In early November 2009, Richardson's wife publicly discussed the affair on television.