From an early age 'Nellie' exhibited the qualities of a hockey player destined for the NHL. Claiming Rookie of the Year honours with the Elk's, he moved up to the Port Arthur Marrs, being named that league's top centre in 1970-71 the year they won the junior League title and competed in the Centennial Cup semi-finals. Making the forward line of the Oshawa Generals of the Ontario Hockey Association, he served with the club from 1971-73, along side fellow Hall of Famers, Lee Fogolin, Rick St. Croix and coach Gus Bodnar.

In the 1973 NHL Draft, he was selected by the Detroit Red Wings as their 2nd choice, going in the 3rd round, 39th overall. Playing for the Red Wing's affiliate in England, the London Lions, he scored 35 goals in 61 games, returning to Detroit the following year where he spent time between the Virginia Wings and the Red Wings. Traded to the Washington Capitals mid-way through the 1974-75 season, he netted his first NHL goal just 13 seconds into his career with the Caps. In his first full season in the NHL, he led the club in goals with 26.

Signed by the Colorado Rockies for the 1976-77 season he entered the history books by scoring the team's first winning goal. With the club for three seasons, he finished up his 7 season NHL career with them in 1979-80 under coach Don Cherry, leaving behind an NHL record of 296 games with 71 goals and 63 assists. Following time with the Philadelphia Firebirds of the AHL and the Fort Worth Texans of the CHL, he returned to Europe playing with teams in West Germany and Austria.

Returning to Thunder Bay following the 1982-83 season, Nelson turned his attention to the building side of the game, as a coach in the minor hockey system, and participating in various hockey schools. Each winter the backyard rink known as the 'Pyatt Gardens' would be the scene of a dedicated father passing along his knowledge of the game he loved so much to his three sons, Jesse, Taylor and Thomas. In 1999 the torch was officially passed from father to son, as Taylor Pyatt was selected 8th overall in the NHL Draft by the New York Islanders, a proud moment indeed for the father who had led the way 26 years earlier.

Inducted into the Northwestern Ontario Sports Hall of Fame, September 25, 1999