The 21-year-old Toffoli played in 10 regular-season games last season, scoring five points in his first career NHL action. He also appeared in 12 playoff contests, scoring six points while the Kings reached the Western Conference finals.
Pearson appeared in one playoff game for the Kings last season, making his NHL debut. Vey also is among Los Angeles' top prospects, but has yet to play in an NHL game.
The moves leave the Kings with 13 forwards on their roster. Los Angeles opens the regular season Thursday at Minnesota.
It's cool when you think about how many great American players have played the game and the two players that were at that 18-game point streak and what they've done in their careers. It's pretty cool right now, but it was kind of overshadowed by the loss.
— Blackhawks forward Patrick Kane after breaking the record for longest point streak by an American-born player with a goal and an assist in a 3-2 overtime loss against the Kings