Helenius had stepped up on just one week's notice to face Joshua after Dillian Whyte was removed from the bout due to a positive test for banned substances.
And now you can see that impressive KO from several different angles.
Will Anthony Joshua fight Deontay Wilder next?
Now that Joshua has won another fight, many fans wondered who he might fight next.
"That's the fight we want," promoter Eddie Hearn said in the ring afterward (h/t ESPN for the transcription). "We have a three-fight plan: Robert Helenius, Deontay Wilder and [WBC champion] Tyson Fury. That's the ambition of the team.
"He's a mature heavyweight now, and against Helenius he took his time to deliver one of the knockouts of the year. He's ready now for some marquee fights. He's smarter now. He's going to take less risks."
And Joshua seems on board as well, "Any time's a good time to fight, It's only a fight. It don't matter who it is. It could've been Wilder eight years ago or Wilder now. It is what it is at the end of the day."