Hendry retired from snooker in 2012 following a quarter-final exit at the World Championship but will return to competitive action alongside Jimmy White, Ken Doherty and James Wattana, who have also been awarded invitational tour cards.
The Scot won 36 ranking titles, with only Ronnie O'Sullivan ahead of him on 37 after winning August's World Championship.
Now 51-years-old, Hendry dominated the sport in the 1990's. He topped the world rankings every year from 1990 to 1998, while his seven World Championships came between 1990 and 1999 and remains unmatched in the modern era.
He is now 100/1 to win any triple crown event and 20/1 to win the 2021 World Championship with Paddy Power.
“I’m excited to have the opportunity to enter some tournaments over the coming two seasons,” said Hendry.
“I’ve really enjoyed picking up my cue again recently at the World Seniors and after some SightRight coaching I feel a little more confident in my game.
"I’ve always missed the buzz of competing and although I have no expectations in terms of performance, this felt like a good time to explore getting back to the table.”
Hendry will be first eligible to play on the World Snooker Tour at the European Masters, scheduled for September 21-27.
The 18-time Triple Crown event winner recently showed glimpses of his old form, reaching the semi-final's of the World Seniors Championship, where he was beaten by eventual champion Jimmy White 4-2.
WST Chairman Barry Hearn said: “I am thrilled that Stephen has decided to return to the tour. He is a giant of the sport and I know that all eyes will be on him every time he takes to the table in the coming months.
“It’s great to know that Stephen’s competitive fires are still burning and given his extraordinary achievements, it was a no brainer to offer him the opportunity to come back. I wish Stephen all the very best for the two seasons ahead.”
Fellow icons White and Doherty will also play on the tour, having competed World Seniors Championship final in August, which The Whirlwind won 5-4, having trailed 4-0, to lift the trophy for successive years.
Hendry career
1969: Born January 13 in Edinburgh.
1983: Wins the Scottish Under-16 Championship.
1984: Wins the Scottish Amateur Championship, aged 15.
1985: Joins the professional tour aged 16 years and three months, becoming the youngest player ever to do so.
1986: Becomes the youngest ever winner of the Scottish Professional Championship and the youngest World Championship qualifier – a record later broken by Belgium’s Luca Brecel in 2012.
1987: Wins his first ranking event, beating Dennis Taylor 10-7 in the Grand Prix final, and adds the British Open title.
1989: Wins the UK Championship against Steve Davis as part of a haul of three ranking titles, and also wins the first of five consecutive Masters crowns.
1990: Retains the UK Championship and wins his first World Championship by overcoming Jimmy White 18-12 in the final.
1992: Claims his second Crucible title, winning 10 successive frames to beat White 18-14 in the final. Also makes his first professional 147 break.
1993: Beats White 18-5 in the World Championship final. The showpiece has not been won by as big a margin since.
1994: Awarded the MBE by the Queen. Wins the world title for the third year in succession and the fourth time in his career after an 18-17 final win over White. Makes seven centuries in beating Ken Doherty 10-5 in the UK Championship final.
1995: Gets the better of Nigel Bond 18-9 in the World Championship final and claims his fourth UK crown against Peter Ebdon.
1996: Wins his fifth successive World Championship, matching Steve Davis and Ray Reardon’s total of six, and completes the World/UK Championship double for the third season in a row. Also wins sixth Masters title with a 10-5 win over O’Sullivan.
1998: Beaten 10-9 after a final-frame re-spotted black by Mark Williams in a memorable Masters final at Wembley.
1999: Wins the last of his seven Crucible crowns, beating Williams 18-11. Makes the first ever 147 in a ranking final at the following season’s British Open.
2001: Beaten 18-17 by Ebdon in the World Championship final.
2005: Wins his last ranking title at the Malta Cup.
2009: Wins his 1,000th frame at the Crucible.
2011: Records the 10th maximum of his career, against Stephen Maguire at the Welsh Open.
2012: Reaches the World Championship having been forced to go through qualifying for the first time since 1988. Marks the opening day of the tournament with a 147 against Stuart Bingham, his third at the Crucible and the 11th of his career, but retires having been beaten 13-2 by fellow Scot Maguire in the quarter-final.
2020: Reaches the semi-finals of the World Seniors Championship, losing 4-2 to eventual champion White, before it is announced on September 1 that he will take up a tour card for the 2020-21 and 2021-22 seasons.
