Akil Thomas scored in his season debut, and David Rittich made 17 saves for the Kings (5-3-2), who had won two in a row.
"We didn't start at all. We took two penalties in the first five minutes, got on our heels," Los Angeles coach Jim Hiller said. "Give them a ton of credit, they came and did what they do, came and worked. [In the] second period, we got ourselves going a little bit. Then in the third period they made big plays when they needed to and we made a couple of poor plays."
Kings forward Kevin Fiala was a healthy scratch after he missed a team meeting.
"I think the statement said it all," Hiller said. "So, there's nothing to add there."
Walman gave the Sharks a 1-0 lead at 2:20 of the second period with a slap shot glove side from the point after Nico Sturm won a battle for the puck off the face-off.
Walman has six points (one goal, five assists) in his past two games.
"I think we can all contribute. We've all kind of individually done it in the past," Walman said. "I think anytime we can help the forwards out, the biggest thing is just getting it up to them. We have so many skilled forwards."