Seamus Conneely played youth football with Mervue United before signing for Galway United in 2007. He spent one year in Galway's U21 side before making the breakthrough into the first team in 2008.

In three years with the Tribesmen he made 86 league appearances before signing for Sheffield United in January 2011. After eighteen months at Brammall Lane Seamus was released by the Blades, at the end of May 2012. On 1 July he signed for Sligo Rovers and made his debut for the club in a 1-1 draw against Bray Wanderers on 7 July 2012. He went on to make 13 league appearances as Sligo won their first league title since 1977. The following year Sligo were displaced by St Pats as league champions but Seamus did pick up an FAI Cup winner's medal as an unused substitute when the Bit O' Red beat Drogheda United 3-2 in the final. Seamus stayed with Sligo for the 2014 season and made 25 league appearances, scoring once, as the Bit O' Red finished fifth in the league table.

In January 2015 Seamus returned to England where he signed for one of his former bosses at Sligo Rovers, John Coleman at Accrington Stanley.

Seamus has also been capped at Irish U21 level.