The charges against Chief Justice Shirani Bandaranayake have raised international concerns that the government is trying to control the judiciary after crushing Tamil rebels in 2009 and consolidating its hold on power.
"We found her guilty," government panel member Susil Premajayantha told reporters in Colombo after tabling the report in the legislature.
The parliamentary panel said it had found Bandaranayake guilty of three out of five charges of financial and professional misconduct brought by the ruling United People's Freedom Alliance.
The charges on which she was found guilty include failing to declare nine bank accounts and interfering in a case involving a company from which her sister had bought an apartment.
The panel cleared her, however, of stashing away 0,000 in an undeclared bank account.
The chief justice has said there is "not one iota of truth" to the charges.
The panel said it had decided not to proceed with nine remaining accusations made by the Freedom