In total, Gallen made 21 appearances in his second season at first-grade level for the Cronulla Sharks, scoring just the one try in the process which was the first try of his career.
Gallen made a total of 17 first-grade appearances for the club in 2003, scoring five tries in the process.
In round 11 against the Manly Sea Eagles, Gallen scored an impressive two tries in his sides 30 points to 28 victory.
In June it was announced that Gallen had "extended his contract for another three seasons"
In the 2004 season, Gallen made a total of 19 appearances for the club and scoring five tries.
Cronulla finished in seventh place and therefore qualified to be involved in the finals series. They were drawn against the second placed side, which happened to be local rivals St. George-Illawarra. In the match Gallen managed to score a try for Cronulla however it wasn't enough to save the Sharks from losing the match 28 points to 22.
Gallen was presented the Cronulla Sharks Chairman's Award in 2005 by the clubs President Barry Pierce after his impressive season where he led the NRL in both hit ups and off loads. At the Dally M Awards, he was also nominated for the position of "Best Lock". However, he lost out to Manly lock Ben Kennedy.
In the 2005 season, Gallen played a total of 25 games in first-grade for the Sharks and in the process scoring six tries.
Gallen won his first ever representative jersey when he was selected to play for City in the annual City vs Country match. In June, Sharks coach Stuart Raper pleaded with the New South Wales selectors to give Paul Gallen an opportunity to prove his worth at State of Origin level. Raper argued that "Gallen's been consistent for us over the past 18 months and if NSW hiccup on Wednesday night...he'll certainly be knocking on the door." After missing out on selection in the first game, Gallen again failed to make selection for the second match. However, after NSW was thrashed by QLD, the NSW selectors made drastic changes to their team by replacing players that performed poorly. He was selected to play in the third and final match which was to be the State of Origin decider, where QLD came from behind to win 16-14.
Gallen was selected to play in the annual Prime Minister's XIII squad to play Papua New Guinea at the end of September. The Prime Minister's XIII defeated Papua New Guinea 28 points to 8 at Port Moresby but Gallen failed to be selected for the Australian Tri Nations squad. At the end of the season, Paul Gallen won the Supporters Player of the Year award
In September 2006, just days after he was voted the Sharks supporters player of the year, Gallen announced that he was considering leaving the Sharks despite having a year left on his contract. Gallen stated that it wasn't the club or coaching staff that made him consider leaving the club but rather the fact that "I just want to play semi-final football". Gallen also stated that he was "looking for a fresh start and a fresh challenge".
In 2006, Gallen made 18 appearances in first-grade for the Cronulla Sharks, scoring seven tries for the club.
In a pre-season trial against South Sydney, Gallen had to be taken from the field with an injury to his ankle. After undergoing an MRI scan on his ankle, Sharks physio Matt Green stated that "the scans have revealed ligament damage but the injury is not as bad as first feared." The injury kept Gallen out until round four of the season when he made his return against the St. George-Illawarra Dragons and he made his first start of the NRL season a week later against the Wests Tigers but only because he was taking painkilling injections before the games. In round 6 against Canberra, Gallen set up a try for Ben Pomeroy before, unfortunately for Gallen, he was forced from the field due to injury during the second half. However, the injury wasn't serious and he was cleared to play in the following round against Newcastle.
It was announced that Gallen had been selected for City to play in the annual City vs Country match but unluckily for him, he was forced to withdraw due to another ankle injury which he sustained in round 7 against Newcastle. The injury however was not serious enough to keep him out for the next NRL fixture against the New Zealand Warriors, but the club doctors believed that his right ankle could not handle playing in the City vs Country match as that would have meant playing three games in the space of six days.
In the match against the Broncos in round 9, Gallen put in another impressive performance, setting up a try in the process. A week later in the match against Canterbury, Gallen sealed the 30-20 points victory with a try in the dying stages of the match and in the process gave the Sharks breathing space. For his effort against the Bulldogs, Gallen was voted as the man of the match. The following week in round 11, Gallen again scored a try in a losing effort against the Roosters.
On June 11 in round 13, Gallen sparked controversy in the local derby match against St. George-Illawarra at Oki Jubilee Stadium in which Cronulla triumphed 20 points to 16. Gallen was accused of taking a dive after copping a high shot by Richie Williams. After the referee awarded the penalty Gallen rose to his feet and winked at his teammates. Gallen defended the incident claiming that he "was hit in the head and it hurt". St. George-Illawarra coach Nathan Brown hit out at Paul Gallen claiming that he "is a tough player, that wouldn't have knocked the top off him." Also in the match, Gallen was placed on report for a head high tackle on Ben Creagh. However, Gallen did manage to set up the first Sharks try for Mitch Brown.
In the days following the game, Gallen continued to come under scrutiny. Gallen explained "We've got a motto here at the Sharks: do whatever it takes to win. That's what I've always done. I'm never going to stop doing that." Gallen continued "we won the game. That's all I care about."
In round 14 against New Zealand, Gallen was again put on report by the referee after a head high tackle on Patrick Ah Van. The judiciary charged him with a grade one careless high tackle which in turn meant that he was suspended for the game against South Sydney in the following round. Cronulla had the bye in round 16 which meant that Gallen hadn't had the previous two weeks to prove himself for selection in the third game of the series in State of Origin. Despite this, Gallen was rewarded for his impressive season to date with a call-up to the New South Wales side for the third State of Origin match, although New South Wales were already 2-0 down in the three game series.
Before the third game of the Origin series, Gallen declared that he "can't wait to be running out and getting booed, I love that sort of stuff. It would mean everything going up there and beating them." After New South Wales had lost the first two games, there was talk that New South Wales lacked passion and Gallen stated that "everybody was sick of hearing it." Just over ten minutes into the match, Gallen put a high shot on Tonie Carroll. Gallen, who was also helped out by his team-mates, then preceded to get in a fight with the opposition. Speaking of the incident after the match, Gallen stated that he and Greg Bird "came here saying that if anyone touches any of us, we're putting it on. I knew it would be a penalty but I knew it would also fire the boys up - it's good for the game."
Gallen was impressive in just his second State of Origin match. In the 55 minutes of the match that he was involved in, he made a total of 127 metres gained as well as making 15 tackles. But even after QLD lost their lock in the first minute, both their wingers during the middle of the game and numerous other injuries to players who couldn't come off due to no more replacements, NSW could not get more than a two point lead until the 72nd minute where they scored two tries, Gallen setting up the final New South Wales try for Hazem El Masri, which in the process capped off a 18 points to 4 New South Wales victory.
After the round 18 loss to the Sydney Roosters, Gallen was charged by the NRL judiciary for a "grade one contrary conduct offence" after he head-butted Roosters' player Shane Shackleton and was subsequently banned for one match.
Round 22 against third placed Parramatta Eels saw the Sharks snap a seven match losing streak in golden point extra time. It was later reported that after the match Gallen was involved in an incident with Reece Williams at winger Dustin Cooper's house. After consuming what was said to be "too much alcohol", team-mates and good friends, Gallen and Williams were involved in a fight. Coach Ricky Stuart stated that although it shouldn't have happened, that there was nothing serious about it as it was only "a scuffle"
At the conclusion of the NRL Premiership, Gallen was rewarded for his fine season with a call up for the Australian squad in a one-off test match against New Zealand on 14th October. However it was announced barely a week before the match that Gallen had to be pulled out of the squad due to a "shoulder injury", with his replacement being Melbourne Storm's Dallas Johnson.
Gallen was selected for all three games in the annual State of Origin series. In the third and decisive game of the series Gallen gave away three penalties and came under heavy criticism from fans for his lack of discipline, in particular for his late hit on Johnathan Thurston. Gallen described the loss as the worst of his career but defended himself saying "they've been saying that those three penalties cost us the game. But there's no way in the world that anyone can say that. Due to his ill discipline in the deciding match, there were calls for Gallen to be sacked as captain of the Sharks but coach Ricky Stuart came out and backed Gallen saying that he should remain the club captain.
In round 18, Gallen scored Cronulla's only try in the top of the table clash in which the Sharks lost to Manly by 34 points to 6. Gallen described the heavy defeat as embarrassing. In the following match against the Newcastle Knights, Gallen was put on report for a high shot on Cooper Vuna. He also gave away several other penalties and claimed that the referees were targeting him.
In 2008 Gallen represented Australia in the Centenary test, scoring a try.
One game for Australia - Centenery test 2008
Hospitable Paul Works to Ensure His Hotel Is the Best; in Association with Fish 4 Jobs Michelle Rushton Meets PAUL GALLEN, General Manager, Sir Thomas Hotel
Oct 05, 2006; Byline: Michelle Rushton AT SCHOOL, it was Paul Gallen's ambition to work in hospitality so, at the age of 15, he secured a place...