Andreas Holmqvist's junior career began in the junior program of Swedish Allsvenskan power Hammarby. At 18 years old he played for Hammarby's J20 team scoring 9 goals and 23 points in 39 games. The following year he moved up to Hammarby's top club in the Allsvenskan, Sweden's second tier league. In 37 games in 2000-2001 he had 5 goals and 18 points with a +26 rating. That year he also made his only appearance for Sweden at the World Junior Championships posting 2 assists in 6 games as the Swedes fell to Canada in the bronze medal match. At year's end he was rated the 22nd best skater in Europe by the NHL Central Scouting Service and the Lightning selected him in the 2nd round of the 2001 Entry Draft. In 2001-2002 Holmqvist had 11 goals and 24 points in 42 games with Hammarby with a +15 rating and 97 penalty minutes. His performance caught the eye on freshly promoted Elitserien club Linkopings which signed Holmqvist for the 2002-2003 season. The young defenseman started strong in the Elitserien but fizzled in the second half of the year finishing with 4 goals and 13 points in 43 games with a -13 rating.
In the summer of 2003, Holmqvist signed a two year, one-way contract with the Tampa Bay Lightning. However, in those two years, Holmqvist failed to develop into the NHLer he was expected to become coming out of Sweden. He spent the majority of 2003-2004 with the Lightning's ECHL affiliate in Pensacola racking up 4 goals and 37 points in 63 games after failing to crack the Hamilton Bulldogs top six in a short 4 game stint in the AHL. In 2004-2005, during the lockout, Holmqvist spent the full season with the Lightning's new full affiliate in Springfield scoring 3 goals and 12 points in 42 games with a -15 rating. Floundering in the AHL due to his defensive limitations, Holmqvist re-signed with Linkopings in the summer of 2005 where he played 46 games scoring 6 goals and 22 points with a respectable +8 rating and 64 penalty minutes. Holmqvist also became a regular for Sweden on the Euro Tour and won a spot on Sweden's gold medal winning World Championships team posting an assist in 9 games.