He took over England while his older brother went off to fight in the Crusades. He is completely greedy and heavily taxed the population to near starvation and used the Sheriff of Nottingham to enforce his laws.
He wants to get rid of Robin Hood to make sure he keeps his gold, believing the poor don't need it because they're poor. He is also terrified of the idea of his brother returning because he'd lose his gold and move back into the guest castle. The Sherrif assures him that Crusades were dangerous and Richard might never return. The Sheriff tells John he believes there's a spy in the castle and hires Tom to catch Jerry in hopes of finding the spy.
The Prince and Sheriff arrange for an archery contest with the winner getting a sack of gold, the title of best archer in the land, and a kiss from Maid Marian as bait to lure Robin hood into a trap. The trap works and Robin goes to prison. When the Sheriff learns that Maid Marian is the spy, he offers to spare her in exchange for being his wife. After she refuses to marry him, preferring the executioner's axe, he runs of to the Prince, whose spies have returned. They inform the Prince that Richard would return in the morning. The Sheriff offers to make sure Richard never returns alive and asks for Marian's execution, terrifying Tom. The Prince rides with the Sheriff and several soldiers. As he rides, John gets excited about the thought of his brother's death. Tom teams up with Jerry and helps save Robin Hood. Robin, with some help from Spike, find out about the Prince's plan for Richard's death and goes off to save him. Robin, with help from Jerry, prevent Richard from being assassinated from the soldiers' arrows and Robin and Richard make it to a broken ship. The two subdue the guards, but get trapped by some ropes used for the sails. The Sheriff and Prince get ready to kill the two but Tom and Jerry fight the two villains, with Jerry fighting the Prince. They buy Robin and the Prince time to escape. Once Richard is free, John begs Richard not to bring their mother into this before he and the Sheriff are trapped in a net.
It is likely he is sent to the dungeons for his crimes.