Iraq's government has set December 18 as the date for the country’s next provincial elections.
Provincial councils play a vital role as the subnational legislative authority, as well as devising localised development plans.
Mr Al Sadr’s call came as a response to an inquiry from one of his supporters about some linked to the Sadrist Movement nominating themselves individually.
“One of the key features of the Sadrist Movement is its unity, obedience and loyalty,” Mr Al Sadr said.
“Your association with corrupt individuals deeply saddens me. Your boycott to the elections brings me joy and frustrates your enemies.”
Mr Al Sadr's influence could sway a considerable number of followers, impacting the legitimacy and inclusivity of the electoral process.
The democratic process was introduced after the 2003 US-led invasion that toppled Saddam Hussein's regime. A boycott might raise concerns about the overall democratic health of Iraq.
The boycott “diminishes its legitimacy domestically and internationally and reduces the influence of corrupt individuals in our beloved Iraq”, said Mr Al Sadr.
In October 2021, Iraq held early elections in response to one of the core demands of a nationwide, pro-reform protest movement that began in 2019 in central and southern parts of the country.
The elections marked the fifth parliamentary vote for a full-term government since the 2003 US-led invasion that toppled Hussein.
But bitter rivalry among political elites, mainly among the country’s majority Shiites, delayed the process of forming a government until October last year.
Mr Al Sadr's efforts to form the government failed despite his movement making a strong showing when they won 73 seats in the 329-seat Parliament.
His desire to form a majority government only with Sunni and Kurdish parties upset his rivals in the Co-ordination Framework, an umbrella group of Iran-backed militias and parties that suffered major losses in the election.
In June last year, he ordered his MPs to resign from Parliament and to withdraw from the country's political process, until it is purged of what he described as “the corrupt”.
The subsequently vacant seats in parliament mainly went to Iran-linked parties, leaving smaller independent parties with a handful of seats in the assembly.
The provincial elections are seen as pivotal as they will be held under a hotly debated electoral system last used in 2018 and abolished in 2020 to calm a nationwide protest movement.
The Sainte-Lague system was reintroduced by parliament in March, despite an outcry from small opposition parties. It has also been opposed by Mr Al Sadr.
The system divides the country into 18 single-seat constituencies, making it difficult for smaller political parties to compete on a provincewide basis.
Previously, a 2021 law introduced by former prime minister Mustafa Al Kadhimi divided the country into 83 constituencies, helping small parties mobilise at the local level and confounding some of their adversaries.