Born in Glasgow, Scotland, he developed meningitis as an infant, which severely affected his immune system and stunted his growth. As a result, he was short and very underweight as a child. Rutherford began weight training after being bullied at school. In 1985, aged 15, and with a body weight of only 79 pounds (36 kg), he took up the sport of powerlifting.

He competed as a junior lifter until 1989. The 5-foot-6-inch personal trainer won 11 championship titles from 1986 to 1990 but then retired.

In March 2007, he promised his nine-year-old son he would make an improbable comeback after watching the film Rocky Balboa, starring Sylvester Stallone, which was all about Rocky being older but making a comeback. 

In 2007, he achieved a silver medal at the European Powerlifting championships,[2] and then bronze at the 2009 World Championships. 

In 2010, he finally achieved his dream of becoming the World Powerlifting Champion at the age of 41. He again won the World Championships in 2011, 2013, 2015, 2019, 2021 & 2022. His daughter Hayley Rutherford and his son Ryan Rutherford have also won their respective divisions at the WDFPF World Championships.

Paul took three years off from competition between 2015 and 2018. He returned to international competition at the World Championships in 2018, achieving a silver medal. He again won his class at the 2019 World Championships held in Halle, Germany. 

Between 2019 and 2021, Paul tore a thigh muscle and contracted COVID-19 twice, which severely hampered his ability to exercise; however, he did manage to pick up his 6th world title in Castleblayney, Ireland, in November 2021.

Paul has been a private trainer and lifestyle management coach for nearly 30 years. His motto is "Keep it REAL" and "let your actions, not your emotions, guide you."