The 26-year old DR Congo international has revealed he was with the win at Anfield on Monday night, stating that he is also pleased to have recovered from a knee injury
The 2-0 win completed a league double for the Baggies over Brendan Rodgers' men, and ended a barren run of no wins in six games for Steve Clarke’s team.
And Mulumbu feels the win was the result of a great team performance, and has helped arrest a worrying slide after West Brom's stunning pre-Christmas form saw them into fourth position after the first 12 games.
"Before the game we were in a bad position so it was really important for us to finish this game to end a bad run," he told the club's official website.
"We did it in great style.
"It was a good performance from all the team and the result was great for us because now we can focus and prepare for Sunderland at home, which is a great opportunity for us to keep climbing up this league."
The 26-year-old also insists he has completely recovered from a knee injury he sustained prior to linking up with his DR Congo team mates for Afcon duty, and is delighted to be back playing again.
"It was great to be back on the pitch and my knee is totally fine now," he added.
"I am glad to be back and winning again because that shows me I am important for the team, and I hope it will keep going for this team.
"I hope I am the lucky mascot and we will keep playing like this every week."