The Company was incorporated on May 28, 1969 under the name União Participações Industriais Ltda., being a pioneer in the petrochemical sector and participating effectively in the installation of the Petrochemical Unit of São Paulo, the first in Brazil. In 1971, it obtained the registration as a publicly-held company and, throughout the 1980s, consolidated its outstanding position in the national petrochemical industry. Since its foundation, it held a 50% stake in Carbocloro, a joint venture with the Occidental Group.

In the 1990‘s and 2000‘s, it participated expressively in the National Program of Destatization in the petrochemical sector and constituted Rio Polímeros – a gas-chemical complex in Rio de Janeiro, started to expand the capacity of the São Paulo Unit and made acquisitions, whose assets were consolidated in Quattor Participações, in 2008, which became the second largest petrochemical company in South America, with Petrobras as partner and whose control was exercised by Unipar, with 60% of the voting capital. In 2010, Unipar sold Braskem its entire stake in Quattor Participações.

In 2013, Unipar acquired 50% of Carbocloro‘s share capital held by the Occidental Group, and now holds 100% of its ownership, thus focusing its strategy on direct action in the soda, chlorine and derivatives sector.

In May 2016, the Company entered into a purchase and sale agreement with Solvay Argentina S.A., a producer of PVC and caustic soda, for the acquisition of 70.6% of Solvay Indupa S.A.I.C. The acquisition was concluded after the approval of the Administrative Council for Economic Defense (CADE) in December 2016 and, in 2017, an additional 17.2% stake was acquired through a takeover bid in Argentina, totaling 87.8% of control and the consolidation of operations.
On January 11, 2018, the risk rating agency Fitch Ratings assigned Unipar the ‘AA-(bra) Long Term National Rating, Corporate Stable Perspective and for its 4th debenture issue. The rating reflects the median position of Unipar‘s business in the Latin American petrochemical sector, the leadership in the Brazilian chlorine-soda market, the healthy history of operating cash generation and margins, in addition to the conservative financial profile, supported by low leverage and adequate debt profile.

In August 2019, a new Public Offer was made for the acquisition of up to all the shares of Unipar Indupa Argentina, with subsequent cancellation of its registration as a publicly-held company, in which shareholders holding 44,150,972 common shares joined. In December 2019, Indupa Argentina received a decision sent by the CNV (Comisión Nacional de Valores), concluding the public offer for voluntary withdrawal and delisting of the shares in BCBA, which now holds 98.4% of the voting capital of the subsidiary.