Ellis went on to win 27 caps for England and was picked for the 2009 Lions tour to South Africa. He made three starts and two further appearances as a replacement, once crucially in the third Test victory at Ellis Park.
"I was sorry to hear the news about Harry having to retire from the game because of injury. He has been an excellent player who always gave everything for Leicester Tigers and England," said Johnson, who captained the 1997 and 2001 Lions.
"From the first time he was involved it was obvious to everyone in the Tigers squad that he was a special talent and that he'd make a big impact for Leicester and England. I'm sure that if he'd been fit Harry would have continued to make a huge contribution to his club and country for many years to come."
Ellis was forced to undergo knee reconstruction following an injury in 2007 and, despite a series of comebacks, he has now been forced to hang up his boots. He won a Heineken Cup medal with Tigers in 2002 when he came off the bench in the victory over Munster at the Millennium Stadium.
He missed the Tigers' 2007 Heineken Cup final defeat by London Wasps in front of a world record club crowd at Twickenham Stadium, after rupturing his anterior cruciate ligament playing against Bristol. He 13 tries in his 44 Heineken Cup outings and played 173 times for Tigers.
He was out of action for 10 months after that injury against Bristol and missed the Rugby World Cup as a result. He battled back to play in the Tigers' 2008/2009 march to their fifth Heineken Cup final, but was only a second half substitute in the defeat to Leinster at Murrayfield.
Having made his Test debut at the age of 22 in the 32-16 win against South Africa in 2004, he won his last England cap in March 2009 in the 26-12 win over Scotland.
It was testament to his character and fighting spirit that he earned a place on the 2009 Lions tour and he started three matches and came off the bench in two others, including the victorious third Test in Johannesburg.
"It took a lot of soul-searching to decide to retire. I was gutted and really upset when I found out and it took a while to get used to," admitted Ellis to the Leiceser Mercury.
"It was a very hard decision to make, but it was also easy on the basis of what it had been doing to me. All last season I was taking a hell of a lot of pain-killers and I was constantly having blood and fluid drained from my knee.
"As well as my rugby, there was also my health to think about. The amount of painkillers I was taking every day was causing my stomach real problems.
"I have had so many operations on my knee in the past that I knew it was time to retire. After the knee reconstruction it was always hard to get back to the levels of fitness that I wanted to be at and then there was a new injury.
"I have a history of problems with that knee and it got almost impossible to play on. I was battling through the pain barrier all the time and it was even affecting me when I wasn't playing.
"I physically could not do it any more because the demands of the game are so great."