San Diego quarterback Philip Rivers took the Comeback Player of the Year award.
They were the first three winners during Saturday night's NFL Honors show.
A second-round pick (61st overall) from Alabama, Lacy was a key performer in the Packers' offense, particularly when star quarterback Aaron Rodgers was sidelined for seven games. He rushed for 1,178 yards on 284 carries (4.1 average), with 11 touchdowns. He also had 35 receptions.
That was good enough for 35 votes from a nationwide panel of 50 media members who regularly cover the league.
"I'm comfortable where I am, and my teammates believe in me, and they make me feel comfortable, so I'm able to play the way I'm capable of playing," said Lacy, who beat out San Diego wide receiver Keenan Allen, who received 12 votes.
Richardson, the 13th overall pick in April's draft on a selection acquired when New York traded star cornerback Darrelle Revis to Tampa Bay, won a close race over Buffalo linebacker Kiko Alonso. Richardson received 23 votes; Alonso, a second-round choice (46th overall), got 19 in balloting announced Saturday night.
Often double-teamed as the season wore on, Richardson made 42 tackles and had 3 1/2 sacks. He clogged the running lanes so effectively that the Jets ranked third against the run this season.
"I'm surprised," Richardson said of beating Alonso and Arizona safety Tyrann Mathieu, who got two votes. "Kiko and Tyrann most definitely had outstanding rookie years and it was a toss-up to me. Kiko made a lot of tackles and Tyrann made a lot of plays down the field. Unfortunately he got hurt, but it was a tight race."
Richardson joked about the possibility of winning both awards - he scored two touchdowns as a fullback in goal-line situations.
"Eddie Lacy beat me out there," Richardson said. "He had a few more touchdowns than I did."
Rivers led the Chargers to a wild-card playoff spot with four straight victories to close out the schedule, giving them a 9-7 record. He led the league with a 69.5 completion percentage and threw for 32 TDs against 11 interceptions.
He received 13 votes in balloting so widespread that 12 players got votes. He was not at the awards show at Radio City Music Hall.