Callum Robinson's 62nd-minute strike proved to be the winner for The Baggies.
Carroll was signed by The Royals last month to make an impact in attack.
But he showed he's useful in both boxes as he produced a miraculous goal-line clearance in the first half.
West Brom had a corner, which Carroll headed away.
However, the 32-year-old's momentum took him into his own goal and it appeared that he would be powerless to stop Robinson's volley from finding the back of the net.
But Carroll produced a miraculous goal line clearance as he was able to get up in a flash and head the ball to safety.
Carroll appeared to headbutt the floor in the process, only emphasising his commitment to keeping the score level.
It was a brilliant piece of defensive work and you can watch it below...
Watch the moment in super slow motion below...
And watch fan footage of Carroll's epic goal-line clearance below...
It's just a shame Carroll's clearance came in a losing effort for Reading.
Many football fans have been praising the English striker for his commitment. View some of the reaction below...
Carroll has made a big impression in his short time at Reading.
Croatian midfielder Alen Haliovic sung his praises last week for the impact he has had at the club.
"He’s helping us in the dressing room because he’s an experienced guy, he’s played a lot of matches in the Prem, he will help us a lot not just on the pitch but outside the pitch as well. It’s good to have him here," he said, per the Reading Chronicle.
“When you have this kind of player where you know at any second he can score or keep the ball, other players from other teams respect him. So it’s easier for us.”