Athlone Town Benson began his career with
Athlone Town, making his debut against
Waterford United in the
Regional Sports Centre on 3 October 2008. He spent the following two seasons playing in the
First Division with the club. After achieving 600 points in his Leaving Certificate examinations, Benson gained a scholarship with
UCD in September 2010. This allowed him to combine his academic studies with football, and he majored in chemistry and maths before earning a master's degree in actuarial science.
UCD Benson was unable to play for
UCD's league side during the closing stages of the 2010 season due to scholarship regulations, however he joined up with the senior squad for the 2011 season, making 20 league appearances in the Premier Division and scoring five goals. Benson became a mainstay of the side during the 2012 season, playing a part in 31 league games for the club and scoring three goals in the process, as
UCD finished ninth and avoided relegation. Benson remained with
UCD for the 2013 season, and scored a career-high nine league goals in 25 appearances during the campaign, as
UCD once more finished ninth. In 2014, Benson was made the captain of the team and played in all 35 league games for the club, scoring three goals. However,
UCD were relegated at the end of the season after losing a play-off to
Galway United. Despite this, Benson chose to stay with
UCD in 2015 as he wished to complete his studies before later making the move to full-time football. He scored the third goal in the 3–0 home defeat of
BATE Borisov to help Dundalk become the first Irish side to reach the play-off round of the
Champions League, and followed this up with a volleyed goal against
Legia Warsaw in the play-off round that received widespread exposure in international media and on social media. Benson considers this to be the greatest goal of his career to date. Dundalk went on to qualify for the
2016–17 UEFA Europa League group stage for the first time and Robbie scored for Dundalk in the home game against
FC Zenit Saint Petersburg, but lost 2-1. He was rewarded for his Champions League displays by being named Soccer Writers' Association of Ireland Player of the Month for August 2016. After considering offers from Scotland and England, Benson signed a new one-year contract with Dundalk in November 2017.
St Patrick's Athletic Benson signed for
St Patrick's Athletic on 13 November 2019, signing for his former teammate
Stephen O'Donnell, who was less than 3 months into his first managerial role. Benson scored on his first start for the club in a 6–0 win over Fermoy in a friendly. On 28 November 2021 Benson scored the winning penalty in the
2021 FAI Cup Final penalty shootout, beating rivals
Bohemians 4–3 on penalties following a 1–1 draw after extra time in front of a record
FAI Cup Final crowd of 37,126 at the
Aviva Stadium.
Return to Dundalk On 17 December 2021, it was announced that Benson had followed head coach
Stephen O'Donnell back to
Dundalk for a second spell at the club.
Derry City On 20 January 2025, Benson signed a one year contract with
League of Ireland Premier Division club
Derry City. On 13 November 2025, it was announced that he would be leaving the club at the end of his contract, having made 29 appearances in all competitions during the season, scoring 1 goal. ==International career==