Harry Kyprianou had volleyed the Shrimpers into the lead after just three minutes but Anderson, who had started for Phil Parkinson, delivered three minutes into the second half.
The former Doncaster Rovers loanee received some great fortune when Southend midfielder Adam King, on loan from Swansea City, headed skyward with the ball bouncing off the hands of visiting keeper Ted Smith and in off Anderson's back.
Not the prettiest way to find the back of the net but it doesn't matter how they go in, according to the man himself.
Felt we did enough to win the game this afternoon but pleased to get a debut goal...doesn't matter how they go in they all count #BWFC
— Keshi Anderson (@KeshMan_) September 3, 2016
Bolton boss Parkinson was thrilled with the debut of Anderson, along with James Henry: “We're very pleased with the new players' contributions.
“It's never easy when you come in and you've only got Thursday to train, but we didn't train much because they'd all had a long day's travelling. Then only an hour yesterday but they're all intelligent players and I'm pleased with their contributions."
Check out the highlights below, courtesy of Bolton's official YouTube channel: