The centre half, who arrived at the club in the summer from Chelsea, scored the equalizer after Tyler Dibling had given the Saints the lead.
Eventually, Ebere Eze got the winner for the London club that saw them move clear of the relegation places.
"It's a massive win," Chalobah told Premier League Productions.
"Obviously coming off a tough game against Bournemouth, we did say we wanted to finish off the year with a win and that's what we've done.
"We didn't start the game well, we were a bit 'stand-offish' - but that goal really woke us up. After that we created a lot of chances, particularly in the first-half. We needed that to wake us up. But luckily we got the three points.
"I'm just trying to chip in here and there, but yeah, as a defender, it's important to get clean sheets, obviously we didn't get that today, but it's nice to chip in the goals as well.
"I was confident that it was going to be a goal, so I wasn't worried about that (the VAR review)."