O'Connor, from Ulverstone, Tasmania began his career at the Essendon reserves after being traded by Geelong in the 1991 AFL Draft for ruckman John Barnes. Even as a young man, O'Connor was known for his massive size (191 cm, 110 kg), considered large even for an AFL player. Despite his bulk and struggle with weight problems, the big man was surprisingly agile and could take strong contested marks.
O'Connor's best year was 1995. He became a centre half forward and strung together a number of impressive games, kicking bags of goals.
1995 put Ryan O'Connor on the map. He stepped up to become an important forward who took the rucking duties in the front half.
In 1997 O'Connor was involved in a car accident which had an effect on his form. He was delisted by the Bombers.
The Sydney Swans picked up O'Connor and used him at centre half forward and centre half back. After a few reasonable seasons, the power forward was delisted at the end of 2000.