Beckham shredded the knee early in the Browns-Bengals game back on Oct. 25 ... and he was finally able to go under the knife Tuesday to repair the issue.

The Browns said in a statement the operation -- performed by world-renowned surgeon Dr. James Andrews down in Florida -- was a complete success.

"Beckham is expected to be ready for the 2021 season," the team added.

Beckham appeared to be pleased with the results of the surgery as well ... he posted a pic of himself post-op and wrote, "Sit back relax n watch how God work.....Now let the journey begin."

Beckham was having his best year as a Brown before the injury ... logging 319 receiving yards and 4 total TDs in 7 starts.

The wideout has vowed to come back stronger than ever ... writing on his social media page earlier this week, "Adversity.... it’s nothin new to me!"

Get well soon!