Mack met his wife, Tara Savage, during his time studying at
Brunel University in 1996. They married in 2005 and live in
East Molesey,
Surrey, with their three children, all of whom have appeared in
Not Going Out: their eldest son, Arlo, briefly appeared in "House", the 2013 Christmas special, their younger son, Louie, appeared in the fourteenth series episode "Dragon Castle", and their daughter, Millie, appeared in the twelfth series episode "Friend". Mack is of distant part-Irish descent, which was explored in the 2018 series of the British television programme
Who Do You Think You Are? While on the show, Mack found that his great-grandfather was a jobbing comic named William Alexander McKillop, who used the stage name Billy Mac. He also learned that his grandfather Joe was born in Southport, but was taken to Ireland as a baby and brought up by his grandparents in
Ballina, County Mayo. In February 2009, Mack, along with other British entertainers, signed an open letter to
The Times regarding the
Baháʼí Faith leaders then on trial in
Iran. Mack said in an interview with
The Guardian that his first foray into comedy was doing
Bobby Ball impressions at his school when he was 15. Ball would go on to play Mack's father, Frank, in
Not Going Out. Mack is a keen supporter of
Blackburn Rovers and occasionally visits
Ewood Park to watch games. In July 2012, Mack received an honorary doctorate from Brunel University. He published his autobiography
Mack the Life (). Mack is a
darts fan and regularly plays with his friend and former
Not Going Out co-star,
Tim Vine. Both men appeared on the debut series of ''
Let's Play Darts, facing each other in the final, with Mack and his partner Martin Adams beating Vine and his partner Darryl Fitton. Mack held two Guinness World Records titles relating to darts, which he achieved on the TV show Officially Amazing''. The first was for the most darts number twos in one minute, which stood until 19 November 2020 when
Ricky Evans broke the record with a total of 25. Mack had also, on the same day of the first record, broken the record for the most darts in inner and outer bullseyes in one minute; that title was held for a year and two months, before it was broken on 23 September 2016 by professional darts player
James Wade. In a 2015 interview with
The Big Issue, Mack stated that he adheres to "
left-of-centre" political leanings. Mack is
vegan. He has been alcohol-free since 2016, and is an ambassador for
Alcohol Concern. Mack has a phobia of flying, and travels by himself to holiday destinations. He travelled by train to
Barcelona and went around the world for
Children in Need in 2009 with other celebrities; however, he and
Frank Skinner did not fly to
Turkey. Mack said because the day he went home was his wife's birthday, he could not get the train back. He went on a flying course, which briefly helped for the flight home; however, he has not been on another plane since. Mack has taken part in several
Soccer Aid matches to raise money for
UNICEF. In September 2021, he scored for the first time, in a year that he played for the World XI team, due to his Irish heritage from his great-grandmother. On 12 June 2022, Mack returned for the
following game at the
London Stadium, and scored the winning penalty for the World XI after a 2–2 draw in normal time. ==Stand-up shows==