They will face Portlaoise in this year's decider.
The win over Portarlington was St Joseph's "best performance" of the season according to their forward Eoghan O'Flaherty.
Mick Dempsey's side ended Portarlington's hunt for four Laois Senior Football Championships in a row with a 1-12 to 0-10 win in the semi-finals on Sunday.
They will now compete in their first decider since 2002 against 35-time winners Portlaoise and will be hoping to claim their first title since 2000.
Former Kildare footballer, O'Flaherty says his side were fully deserving of their victory:
Portlaoise against Graiguecullen is sponsored by LOETB Portarlington Further Education and training Centre... now enrolling for January 2024 courses visit portarlington fetc.ie, facebook or call for more details 057 86 23161
And Laois Leisure, Portarlington and Portlaoise, visit laoisleisure.ie
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