The following year, in his first full-length campaign in the NHL, Gonchar tallied 41 points, showing his potential as an effective offensive defenceman.

On 3 March 2004, in his tenth season with the Capitals, Gonchar was traded to the Boston Bruins in exchange for Shaone Morrisonn and two draft picks.

In addition to his on-ice duties for the Penguins, Gonchar housed rookie Evgeni Malkin when he first arrived from Russia in October 2006.

[9][10] With the Penguins struggling to make the playoffs, Gonchar returned to play his first game of the season on 14 February 2009, against the Toronto Maple Leafs after being sidelined for 21 weeks.

[11] He played in the final 25 games of the regular season and tallied 19 points, helping the Penguins into the 2009 playoffs as the Eastern Conference's fourth seed.

[13] Gonchar and the Penguins went on to win the Stanley Cup in seven games, facing the Detroit Red Wings for the second consecutive year.

Gonchar finished the season third in points-per-game average among defencemen (behind Norris Trophy nominees Mike Green and Duncan Keith).

During the 2012–13 NHL lockout, Gonchar returned to his native Russia to play with the Kontinental Hockey League (KHL)'s Metallurg Magnitogorsk.

[20] Gonchar remained un-signed over the summer, and accepted an invitation to return to the Pittsburgh Penguins' training camp on a try-out basis on 14 August 2015.

Gonchar signalled the end of his professional playing career in accepting a development coaching position within the Pittsburgh Penguins organization on 27 October 2015.

[22] On August 12, 2020, it was announced that Gonchar's contract, along with those of fellow assistant coaches Mark Recchi and Jacques Martin, would not be renewed for the next season.

Both individuals enjoyed long, successful playing careers as NHL defenceman and together provide a wide range of expertise on both sides of the puck.

Gonchar met his future wife, Xenia Smetanenko, then a figure skater for Armenia, at the 1998 Nagano Olympic Games.