21st September 2017, 12:01 | Widnes
The 40-year-old Cummins, who has been involved in rugby union since being sacked by the Bulls in 2014, succeeds Australian Brett Hodgson, who has been appointed as an assistant coach at Wests Tigers.
Betts said: "Francis has great experience as a player and a coach and will enhance us as a group. He has worked hard within coaching for many years, proving his abilities in tough environments.
"It was important for me to find a coach who has played at the highest levels as an outside back and can relate well to our players in these positions. This appointment makes our coaching team stronger and I am looking forward to working alongside Francis next season."
Former winger Cummins made 358 appearances for Leeds Rhinos from 1993 to 2005 and still holds the record as the youngest player to appear in a Challenge Cup final at Wembley. He was just 17 years and 200 days old when he played against Wigan Warriors in 1994.
"I'm delighted to be joining Widnes Vikings and to be back in rugby league," he said. "I'm looking forward to using the experience from my playing career and my 12 years in coaching to support the progress of the Vikings, alongside Denis and the coaching team."