He first came to prominence on the club scene at underage levels; however, he experienced little success with the St Finbarr's minor or under-21 teams.
In 2007, after fifty years of playing in the top flight of the County Senior Football Championship, St Finbarr's were relegated to the intermediate level.
St Finbarr's won by 2–13 to 0–14, giving Shields a County Premier Intermediate Championship winners' medal.
[1] Following this promotion, St Finbarr's would lose consecutive Senior finals in 2009 & 2010 to Clonakilty and Nemo Rangers respectively.
These years of hurt finally came to an end in 2018 when the Barrs' beat Duhallow in the decider, giving Shields his first Senior county winners medal.
St Finbarr's defeated Clonakilty in the 2021 final on a scoreline of 0-14 to 0-13, adding another county medal to his collection.
Colm O'Neill and Daniel Goulding combined to score two goals and to help Cork to a narrow 2–10 to 0–15 victory.
[4] After impressing in some challenge and McGrath Cup games in 2005, Shields was handed his senior championship debut in the 2006 Munster final against Kerry.
The quirks of the championship saw Cork face Kerry again in the subsequent All-Ireland semi-final for the third time in five seasons.
In a similar pattern to previous encounters Cork failed to beat Kerry at Croke Park.
Cork gave a good account of themselves; however, Kerry could not be beaten and Shields's side went down on a 1–15 to 1–13 score line.
A defeat by Kerry in a replay of the provincial semi-final resulted in Cork being exiled to the All-Ireland qualifiers.
After negotiating their way through a difficult series of games, Cork defeated Dublin to qualify for their third All-Ireland final in four years.
At the full-time whistle Cork were the champions by 0–16 to 0–15 and Shields picked up an All-Ireland winners' medal.
That year Munster reached the Railway Cup final against Ulster; however, the northern province emerged victorious by 1–12 to 1–8.
[11] In November 2007, following a successful three-week trial[12] with top level Australian rules football club Carlton, Shields signed a two-year international rookie contract,[13] becoming the third Cork native to sign with the club, joining former hurlers Setanta and Aisake Ó hAilpín.
After the first half of the season, however, he decided to return to Ireland in July 2008, saying he "missed home" and Australian rules football "wasn't for him".