Liam originally completed a move to Alfreton Town in September 2008. The Reds beating off interest from a number of other clubs to clinch his signature.
At the Impact Arena he scored 71 goals in 110 appearances. The striker netted 31 goals in his final season as Alfreton won promotion to the Conference Premier, finishing as top scorer in Conference North. This also earned him the Divisional Player of the Season award for 2010/2011.
Hearn signed for Grimsby Town in June 2011 for £30,000. His first goal for the Mariners came 11 games into the 2011/12 season against Wrexham. He was voted "Supporters Player of the Season" in April 2012, also picking up five other awards, finishing the season with 29 goals from 51 appearances.
He then signed for Mansfield Town in June 2014, then joined Conference Premier side, Lincoln City after turning down a new deal at Field Mill.
In May 2016, Hearn signed for Ilkeston FC, finding his way back to the Impact Arena in August 2016.