Hull City Holohan came through the ranks with
Kilkenny City in his native Ireland and was picked up by Hull City in 2008. He went on to spend the next four years with the Tigers but failed to make an appearance, only making the bench once for an
FA Cup tie against
Wigan Athletic.
Alfreton Town Holohan was signed by
Alfreton Town in 2012 following his release from Hull. He also trialled with
Carlisle United and
Hibernian.
Drogheda United After being released by Alfreton, Holohan signed for
League of Ireland side
Drogheda United. Holohan enjoyed a successful campaign in the 2014 season, scoring 8 goals in 32 games and winning the supporters' player of the year award. He helped Drogheda progress to the quarter-finals of the
FAI Cup by scoring 3 goals in 3 games but was one of three Drogheda players sent off in their exit against the eventual champions
Derry City.
Cork City In November 2014, Holohan left to sign for
Cork City. During his two years at Cork, Holohan won the
FAI Cup in 2016 and scored in the
President of Ireland's Cup final to help his side win 2–0.
Galway United Holohan later joined
Galway United and scored his first career hat trick in a 4–1 win over his former side Drogheda United.
Waterford After suffering relegation with Galway United, Holohan signed for
Waterford following their promotion to the top flight. He helped the club finish fourth and while this would have qualified the club for the
Europa League first qualifying round, Waterford were ruled by
UEFA to have not passed the "three-year rule" as the club were reformed in 2016.
Hartlepool United Holohan signed with English
National League club
Hartlepool United on a short-term contract in 2019. Having had to wait for international clearance before being able to play, Holohan eventually broke into the first team and scored his first goal in English football in a 1–1 draw against
Aldershot Town in April 2019, an equaliser which ultimately relegated his opponents. Holohan impressed in the seven games that he played and did enough to earn an extended contract. In the
2019–20 season, Holohan scored nine goals and contributed seven assists. Holohan then signed a contract until the end of the
2021–22 season due to this good form. Holohan scored his 10th goal of the
2020–21 season in a 2–0 win against
Notts County. This goal was also his fourth consecutive goal after scoring against
Stockport County,
Dagenham & Redbridge,
Boreham Wood, and
Notts County respectively. Holohan started in the
2021 National League play-off final as Hartlepool were promoted back to the
Football League. In August 2021, Holohan scored Hartlepool's first goal back in the Football League in a 1–0 victory over
Crawley Town. In a 2–1 win over rivals
Carlisle United, Holohan scored his final goal for Hartlepool. This would subsequently be voted as
League Two goal of the month for August. Holohan struggled for game time during the
2021–22 season and departed after making 108 appearances and scoring 23 times.
Grimsby Town On 22 March 2022, Holohan signed a two-year deal with
National League side
Grimsby Town. On 23 May 2022, with Grimsby trailing 1-0 to
Notts County in the
National League play-offs in the final minute of added on time, Holohan scored an equaliser to send the game to extra time, with Grimsby going on to win the game 2-1 and advancing to the semi-finals. Holohan played in the
2022 National League play-off final as Grimsby beat
Solihull Moors 2–1 at the
London Stadium to return to the
Football League. During an
FA Cup fourth round tie at
Championship side
Luton Town, Holohan scored the opening goal in a 2–2 draw. On 1 March 2023, he scored two penalties in a 2–1 victory at
Premier League side
Southampton in the fifth round of the
FA Cup, securing Grimsby's first quarter-final appearance since 1939. Holohan was released at the end of the
2023–24 season.
Crawley Town Holohan joined Crawley on a free transfer in July 2024 after his release from Grimsby Town joining former teammate
Toby Mullarkey, also from Grimsby, who joined on the same day. Holohan initially struggled for game time at Crawley and didn't make his first appearance for the club until October 2024 in a 4–3 home defeat against
AFC Wimbledon in the
EFL Trophy. ==Career statistics==