The scandal erupted in June last year when the country's former spy boss filed a complaint with the police alleging that Ramaphosa had concealed the 2020 theft of a huge haul of foreign currency from his Phala Phala farm.
An investigation by the ombudswoman, also known as the public protector, found that Ramaphosa's handling of the case was not in violation of the constitution.
"Aggregated against the standard imposed by the executive ethics code it is found that there is no basis upon which to conclude that the president contravened" the relevant clauses of the law, "including the period following the alleged theft of US dollars", interim ombudswoman, Kholeka Gcaleka told a news conference in Pretoria.
The public protector's office is an independent state institution provided for in the constitution and reports on misconduct or malfeasance within the government. But it has no powers to prosecute.
The police is carrying out its own investigation in the farm heist case which raised accusations of money-laundering and corruption by the 70-year-old president.
Ramaphosa has always denied any wrongdoing.
He said the cash - more than half a million dollars stashed beneath sofa cushions - was payment for buffaloes bought by a Sudanese businessman.
A parliament-sanctioned independent panel said last year that he "may have committed" serious violations and misconduct.
Parliament later decided not to initiate impeachment proceedings that could have forced him out of office.
Ramaphosa, a former union boss who became a business tycoon after apartheid, stepped into the president's job in February 2018.
He came into office promising a "new dawn" after the scandal-rocked tenure of former president Jacob Zuma.
JOHANNESBURG — South Africa's corruption watchdog on Friday absolved President Cyril Ramaphosa of allegations that he breached executive ethics in a farm cash scandal that spawned into one of the biggest storms of his career.