He joined Wrexham's Conference Premier rivals York City on 22 January 2009 on loan until the end of the season, after having made 20 appearances and scored 1 goal for Wrexham up to that point in 2008–09. Following the move, Mackin said "I need a change of scenery. We have a large number of players at the Racecourse at present and it's difficult to get into a side that's doing well and getting the results". He made his debut in a 2–1 defeat away to Eastbourne Borough on 24 January 2009 and was described in "The Press" as looking "off the pace". Mackin played for York in their 13–12 penalty shoot-out victory at home to Kidderminster in the FA Trophy third round on 12 February 2009, which had finished 1–1 after extra time. A tight thigh resulted in him missing a match against Oxford United in April 2009 and he made his return later that month in a 0–0 away draw with Barrow. Following the close of the league season, Mackin was described in "The Press" as one of York's most consistent performers throughout the season. He started in the 2009 FA Trophy Final at Wembley Stadium on 9 May 2009, which York lost 2–0 to Stevenage. According to "The Press", he was "hardly noticed" in the match before receiving a yellow card for "scything down" Darren Murphy. He finished the loan spell with 21 appearances, and after returning to Wrexham was released after spending around a decade with the club.