Carroll made his maiden appearance for West Ham since May, and his first since making a big-money permanent move from Liverpool in June.
A heel problem followed by a double fracture of the right foot kept Carroll on the sidelines, but the powerful striker replaced goalscorer Carlton Cole in the 72nd minute of Saturday's match in Wales.
And he quickly made an impact, setting up Mark Noble's injury-time strike that sealed West Ham's win.
"I'm buzzing to be back," an excited Carroll said.
"It's a great feeling to be back after being out for so long. This was my first game back so obviously I was a bit rusty.
"But I was happy to set up the goal at the end and I'll try to forget about the rusty bits."
West Ham assistant manager Neil McDonald believes Carroll's return will give the club a big boost, and has tipped the 25-year-old to play a key role in their bid to avoid relegation.
"That (Carroll's return) is going to make the squad stronger, for competition for places," he said.
"When he (Carroll) came on I thought the crowd got behind him; they've seen the players who want to wear the shirt and have given everything.
"I think Andy typified that when he came on, holding the ball up, flicking it on and making the pass for Mark Noble to score the second goal.
"He gets stronger as time goes on to progress with training and games, and I'm sure he will make a big difference for us."
West Ham climbed out of the bottom three with victory, just their fourth in the league this season.
The win came at the end of a tough week for manager Sam Allardyce, who oversaw 5-0 and 6-0 defeats in the FA Cup and League Cup respectively.
