Leipheimer was a team-mate of Armstrong for five years at the US Postal Service, Astana and RadioShack teams.
A statement read: "Omega Pharma-Quick-Step Cycling Team announces that the contract with Mr Leipheimer has been terminated, effective immediately.
"We commend the rider for his open co-operation with USADA and contribution to cleaning up the sport of cycling. "However, in the light of the disclosures made by Mr Leipheimer in his public statement on 10th of October the team has decided to terminate the contract.
"This decision has the full support of the team owner, the board represented by Mr Bessel Kok and team manager Mr Patrick Lefevere."
Leipheimer is currently serving a reduced six-month suspension for doping violations.