As a law student, Attorney Hannon worked for Greater Boston Legal Services in civil litigation and client representation.  She also worked with the Massachusetts Public Defender's Office as a student public defender.  This position afforded her the opportunity to take a case from arraignment through appeal and oral argument before the full bench of the Supreme Judicial Court of Massachusetts.

Upon graduation and admittance to the bar, Attorney Hannon was appointed Assistant District Attorney in Essex County, Massachusetts, where she represented the Commonwealth of Massachusetts at bench and jury trials in misdemeanor and minor felony cases.

Attorney Hannon later began practicing law in the private sector.  She was employed by a Salem, Massachusetts firm until she opened her own practice in Lynn, Massachusetts in 1983.  After returning to Illinois, she opened a general practice in Barrington, Illinois in 1988 with emphasis on family law and real estate.  In 1995, Attorney Hannon restructured the practice to focus on probate, guardianship, elder law, estate planning and real estate, which is in full operation today.

Attorney Hannon is a member of the Chicago Bar Association, the Illinois State Bar Association, the Northwest Suburban Bar Association and the National Association of Elder Law Attorneys.