The former British, European and Commonwealth heavyweight champion, known as Our Enry passed away on Sunday, aged 76.
He will be best remembered for flooring a young Cassius Clay in 1963 only to be stopped on cuts, as he was when the pair met again three years later.
Cooper never captured a world title but McGuigan still believes he was as popular as any fighter in British boxing history.
"He was just such a lovely human being," he told Sky Sports News HD.
"What you see is what you got, he was a great fighter in the ring, he didn't reach the pinnacle of the heavyweight division because he wasn't a big heavyweight - he was more cruiserweight by today's standards.
"But he fought the best and he was honest and honourable outside the ring as much as he was in it. He always had great respect and something nice to say about everybody - including his opponents.
He was a genuine upstanding guy. He had a huge impact on everybody's career because he was so famous. He came around at a time when television was being watched an awful lot more, boxing was huge sport.
"He was a huge icon, he won Sports Personality of the Year two times in a row, he was the only boxer to be knighted.
"His popularity outside of the ring was enormous; he made 10 times more outside of the ring than he made in it, which is an indication of the type of respect he had from the general public."
Tributes have been pouring in from across the sporting world.
The likes of David Haye and Amir Khan have been quick to pay their respects and McGuigan says that although he belonged to a bygone era in boxing, Cooper is the perfect rold model for today's professionals.
"He was a larger than life character," he said.
"There are certain people in the game that transcend the sport; there are lots of champions that are forgotten, but Cooper had such an impact on everybody and he was such a lovely man.
"You got what you saw. He was an honourable upstanding man, great dignity, a great presence.
"He always said the right thing, never criticised his opponents and always did his talking when the bell rang; a lot of young guys coming up could learn a lot from Henry Cooper.
"He was a wonderful, wonderful man and we'll never forget him."