When Richardson was appointed as the replacement for Matt Taylor in December, the Millers were already eight points adrift of safety in the Championship standings.
Just 13 points had been accumulated from their 20 league matches, but Richardson has failed to improve Rotherham's fortunes since his arrival.
A total of 18 defeats have been posted from 24 games in all competitions, with the Yorkshire outfit recording two wins and four draws in the other six fixtures.
There have been times in recent weeks when Rotherham have shown signs of life, but an inevitable relegation soon followed the 2-1 victory over Millwall.
Rather than keep Richardson at the helm for next season's League One campaign, the Rotherham hierarchy have opted for a change in direction.
Steve Evans returns to Rotherham for second spell in charge
In the hours after Richardson was sacked, Rotherham revealed that Evans had agreed to return to the club, eight-and-a-half years after his previous stint.
Evans has been spearheading a surprise League One promotion charge for Stevenage all season, but that has since tailed off during the run-in.
That has enabled Evans to make an immediate move back to a club that he guided from League Two to the Championship between 2012 and 2015.
The 61-year-old posted 72 wins and 56 defeats from his 173 matches in charge, with that period in charge impressive enough to earn him the Leeds United job soon after his departure.
Speaking to the club's official website, chairman Tony Stewart said: "On behalf of everyone at Rotherham United, I'm absolutely delighted to welcome Steve Evans and Paul Raynor back to the football club.
"Leam and Rob's (Kelly) departure was not something we took lightly, but following extensive conversations at Board level, it was unanimously agreed that a change of direction was needed to give us the best possible chance of bouncing back to the Sky Bet Championship at the first time of asking.
"In Steve and Paul, we have two individuals that understand the Rotherham United 'DNA' and know what it takes to build a successful team. They have a proven track record of success at a plethora of clubs, including our own."
Evans will be in the dugout for Saturday's Championship fixture at home to Birmingham City on Saturday.