He later made his senior debut for his native-county at the age of 18 in 2006. That year Limerick made it to the National Hurling League Div 1 final but lost out to Kilkenny.
Limerick's hurling fortunes were on the up at the time. They defeated Tipperary in a three-game Munster semi-final saga in 2007, however, they lost the subsequent Munster final to Waterford. Limerick later gained revenge by defeating 'the Desie' in the subsequent All-Ireland semi-final, setting up an All-Ireland final meeting with Kilkenny on 2 September 2007. Limerick were beaten on the day as Kilkenny picked up their second All Ireland title in a row. Hickey later picked up the Young Hurler of the Year award.
2008 was not as successful as the two years before for Limerick they went down 4-12 to 1-16 to Clare in the Munster Championship Semi Final. They then entered the Qualifiers at Phase 3 where they were well beaten by Offaly ending Limerick's championship for another year.
2009 saw Hickey's side take Waterford to a re-play in the Munster Championship Semi Final but lost out in the re-play. So once again Limerick went into the Qualifiers this time at Phase 2, they beat Wexford by 1-13 to 0-14, they then played Laois in the next round and again ran out winners on a 0-20 to 1-14 scoreline. They played Dublin in the All Ireland Quarter-final, despite entering the game as underdogs they ran out 2-18 to 1-17 winners to set up a semi final with fellow Munster side Tipperary. That game turned out to be a game to forget for Hicky and co as Tipperary ran out 6-19 to 2-07 winners.
2010 saw a falling-out between many of the senior Limerick players and manager Justin McCarthy which resulted in a number of players being dropped from the team. Hicky played no part in Limerick's championship season.
In late 2010, Dónal O'Grady was appointed as Limerick manager and many of the players who had been dropped the year before returned. Limerick, who were now in Div 2 of the national League went the whole campaign unbeaten including the final where they overcame Clare to give Hicky a Div 2 winner's medal, his first medal he had won with Limerick.