*Club domestic league appearances and goals, correct as of 09:32, 25 November 2024 (UTC) ‡ National team caps and goals, correct as of 19:11, 15 October 2024 (UTC)
On 25 July 2021, it was announced that Curtis, as well as his brother Ben, had signed for St Patrick's Athletic, where they would initially play with the club's under 19 side.[8] Curtis made his senior debut for the club came on 13 August 2021, replacing the injured Lee Desmond in injury time of a 2–1 win over Waterford at Richmond Park, making him the club's youngest ever player at 15 years and 255 days old (this record has since been taken by Mason Melia in 2023).[9][10] He made his UEFA Youth League debut on 29 September 2021 in a 2–1 loss to Serbian side Crvena Zvezda.[11]
2022 season
Both Sam and brother Ben Curtis signed their first professional contracts on 20 January 2022.[12][13][14] Curtis' first start for the club came on 6 May 2022 in a 4–0 win away to Drogheda United at United Park.[15] His form in May 2022 saw him voted as the club's Player of the Month by supporters.[16] His first appearances in European competition came in the summer of 2022 when he came off the bench in a 1–1 draw with NŠ Mura of Slovenia[17] and in a 1–0 away win against Bulgarian side CSKA Sofia in the UEFA Europa Conference League.[18] He won the clubs' Player of the Month award for the second time in the season, for September 2022.[19] He made a total of 20 appearances in all competitions during his first full season at the club.[5] His form in his breakthrough season at the club led to reported interest from Manchester City and Chelsea.[20][21][22][23][24][25]
2023 season
Curtis started the 2023 season off well, making the Right wingback position his own following the departure of Barry Cotter in the offseason. He started the first 6 games of the season in the position, leading up to the March international break which earned him his first callup to the Republic of Ireland U21 side with Pats assistant manager Jon Daly tipping him for a bright future in the game.[26] He earned the club's Player of the Month award for his performances in March 2023.[27] On 19 May 2023, Curtis scored the first goal of his senior career, heading home a Jake Mulraney corner in a 1–0 Dublin derby win away to Shelbourne at Tolka Park.[28] He was voted as the club's Player of the Month for the second time in the season for May 2023.[29] On 30 June 2023, Curtis scored a header from a Jake Mulraney corner to give his side a 3-goal lead in an eventual 7–0 win over UCD at Richmond Park.[30] On 4 August 2023, he scored his 3rd goal of the season, volleying home his sides second goal in a 2–0 win away to Sligo Rovers at The Showgrounds, in what was his 50th appearance for the club in all competitions.[31] On 28 October 2023, he was named as the club's Young Player of the Year for 2023.[32] On 12 November 2023, Curtis was part of the starting XI in the 2023 FAI Cup Final, in a 3–1 win over Bohemians in front of a record breaking FAI Cup Final crowd of 43,881 at the Aviva Stadium.[33] On 15 November 2023, it was announced that Curtis had been included in the PFAI Team of the Year and was one of the 3 nominees for the PFAI Young Player of the Year award, alongside James Clarke and Jack Moylan.[34] On 2 December 2023, he was named PFAI Young Player of the Year for 2023, becoming the youngest ever player to win the award.[35][36]
Sheffield United
On 25 January 2024, Curtis signed for Premier League club Sheffield United for an undisclosed international training compensation fee, on a contract until 2027.[37][38][39] He was named in the squad for the first time on 25 February 2024, but remained an unused substitute in a 1–0 defeat to Wolverhampton Wanderers at Molineux.[40] On 11 May 2024, he made his debut for the club, coming off the bench in the 63rd minute of a 1–0 loss away to Everton in the Premier League.[41]
Peterborough United loan
On 2 August 2024, Curtis joined EFL League One side Peterborough United on a season long loan deal.[42] He made his debut for the club on 10 August 2024, in a 2–0 loss at home to Huddersfield Town on the opening day of the season.[43]
International career
Curtis featured for the Republic of Ireland U15 side in 2019, captaining the side at age 13.[44] He was a prominent player for the Republic of Ireland U17s during their qualification campaign over 2021–2022, scoring 2 goals in 6 appearances.[45][46][47][48] Curtis captained the Republic of Ireland U18 side over 2021–2022.[49] His first call up to the Republic of Ireland U19 team came in September 2022.[10] Curtis received his first call up to the Republic of Ireland U21 side came in March 2023, for a friendly against Iceland U21, despite still being just 17 years old.[50][51] He played the full 90 minutes in the game as his side came from behind to win 2–1 after playing an hour with 10 men.[52] On 20 June 2023, he was named as Republic of Ireland U18 Player of the Year for 2022 at the FAI International Football Awards.[53] On 6 September 2024, he scored his first goal for the U21s, scoring an 84th minute winner in his sides 1–0 victory away to Turkey.[54]