Richards suffered an upper-body injury during Thursday's 2-1 win over Florida when Panthers forward Sean Bergenheim leveled him with a high check in the second period.
The 26-year-old has totaled 11 goals and 20 points in 25 games in his first season with LA.
Penner, on the other hand, returns to action for the first time since sustaining a hand injury in a November 10 contest with Vancouver. Prior to the setback, the seven-year veteran recorded only a pair of assists in 14 games.
The Kings also revealed that defenseman Willie Mitchell, who departed Thursday's game in the first period with an upper-body injury, will miss multiple games.