He was selected by the Los Angeles Kings in the fourth round (99th overall) of the 1997 NHL Entry Draft, and spent most of his professional career in Europe.

Sean Blanchard started his junior hockey career with the Valley East Cobras of the Great North Midget League.

Upon turning professional, Blanchard split time between the Springfield Falcons of the AHL and the Mississippi Sea Wolves of the ECHL, both of whom were the Kings' farm teams.

[5] He would spend the majority of the season with the Sea Wolves, and helped the team win the Kelly Cup, beating the Richmond Renegades in the finals.

[6] The Kings would change their farm teams in the off-season, and as a result Blanchard would spend the 1999–00 season with both the AHL's Lowell Lock Monsters and the ECHL's Trenton Titans.

The following season, Blanchard would primarily play for Florida Everblades of the ECHL, but would also dress for the Grand Rapids Griffins and Manitoba Moose, both of the IHL.

This, coupled with the Ayr Scottish Eagles and Manchester Storm also folding, and the Bracknell Bees deciding to drop down to the BNL, culminated in the demise of the BISL.

At the culmination of the season, Blanchard remained in Germany, but moved to the Hamburg Freezers, registering 20 points in 51 games as the team finished 8th.

[17] The team lost in the quarterfinals to Russia, during which game Blanchard registered his only point of the tournament, assisting on a Daniel Tkaczuk goal.