Kucherov signed an eight-year, $76 million contract extension (average annual value $9.5 million) that begins next season. The 25-year-old set an NHL career high with 100 points (39 goals, 61 assists) in 80 games last season and has increased his points each of the past four seasons.
McDonagh and Miller were acquired from the New York Rangers in a trade Feb. 26. McDonagh, 29, signed a seven-year, $47.25 million contract extension (average annual value $6.75 million) that begins next season. Miller, 25, signed a five-year, $26.25 million contract (average annual value $5.25 million) before becoming a free agent.
"These are players we knew wanted to sign, they are the core of our team and important players on our team," Yzerman said. "Our intention was to get Nikita's next contract done as soon as possible. He's an extremely important player to us."
The emergence of Kucherov has allowed center Steven Stamkos to settle into a playmaking role, and he thrived last season with 86 points (27 goals, NHL career-high 59 assists) in 78 games. Miller had 18 points (10 goals, eight assists) in 19 games with the Lightning playing on their line.
Brayden Point will center the second line after the 22-year-old had a breakout season with 66 points (32 goals, 34 assists) and established himself as Tampa Bay's top two-way forward. Ondrej Palat will be at one wing with Tyler Johnson or Yanni Gourde playing the other.
The Lightning allowed 234 goals last season, 13th in the NHL. Victor Hedman won the Norris Trophy voted as the NHL's top defenseman last season; the 27-year-old had 63 points (17 goals, 46 assists) and was plus-32 in 77 games.