His early career was spent playing for his hometown team, Toulouse, in the Top 14 and in the Heineken Cup.

Michalak made his first appearance for France against South Africa on 10 November 2001 and became a regular on the French side.

Michalak's club Stade Toulousain were crowned the champions of France in 2001 when they defeated Montferrand in the final 34–22.

He was then promoted to the starting line-up for a test against Australia the following week in Marseille by head coach Bernard Laporte.

Toulouse proceeded to win the 2002–03 Heineken Cup, defeating fellow French team USA Perpignan 22–17 in the final.

[4] Michalak was then included in the national squad for the June tests prior to the 2003 World Cup in Australia.

He also scored a try in the subsequent game against Scotland and was rested for the final pool match against the United States.

Michalak was superb in France's 43–21 quarter-final win over Ireland in Melbourne, landing all nine goal attempts (four conversions and five penalties) for a personal haul of 23 points.

He played in all of France's 2005 Six Nations matches, as well as Toulouse's 2004–05 Heineken Cup victory over Stade Français.

He came into the Heineken Cup final under an injury cloud, but showed no signs of it, even sealing the victory for Toulouse in the end with a late drop goal, having also scored two earlier penalties.

Within seconds of coming as a substitute on in the quarter-finals of the tournament, he made a break and then made an uncalled forward pass to Yannick Jauzion who scored a try which when converted gave France a two-point lead which they held onto to beat New Zealand, the tournament favourites.

In March 2010, in a match against rivals Stade Français, Michalak tore cruciate ligaments in a knee and was stretchered off.

[12] The Sharks' need to fill vacancies left by injuries to several of their scrumhalves is widely considered a key short-term motive for the signing; in the 2012 season, he is seen as an extra option at fly-half, a position where they had issues in 2011.

[14] After over two years out of international rugby, Michalak was recalled by new coach Philippe Saint-André for the 2012 mid-year test series in Argentina.

[17]In the final match of the 2013 Six Nations championship, Michalak suffered a dislocated shoulder ruling out any club rugby for 3 weeks.