Labour 20 (L20) was established in 2011, by the French presidency. The L20 has the aim of promoting debate and articulating recommendations on issues affecting and involving the global working class. The group brings together the main leaders of trade union organisations.

The Urban 20 (U20) was established in 2018 with the co-chair of Buenos Aires and Paris and is a city diplomacy initiative that brings together cities from the G20 member countries with the aim of promoting debate and the political articulation of recommendations on the economic, climate and development agendas in cities. The U20 initiative is permanently convened by C40 Cities and United Cities and Local Governments, under the leadership of one or two host cities that change every year. Previous U20 cycles have been chaired by Buenos Aires and Paris (2018), Tokyo (2019), Riyadh (2020), Rome and Milan (2021), Jakarta and West Java (2022) and Ahmedabad (2023).

Science 20 (S20) or Ciência 20 (in Portuguese) was established in 2017 by the German presidency with the aim of promoting debate and articulate recommendations on science and technology agendas. The group is made up of the national science academies of the G20 countries and promotes an official dialogue between the scientific community and policymakers. Similar to the G20, the S20 has a non-permanent rotating secretariat and operates as a forum (rather than an organisation), with its summits being held annually, usually before the respective G20 Summit. During the 2024 edition in Brazil, the meetings will be organised by the Brazilian Academy of Sciences.

The Superior Audit Institution 20 (SAI20) or grupo das Instituições de Controle 20 (in Portuguese) was established in 2022 by the Indonesian presidency and aims to promote debate and articulate recommendations on transparency, accountability and anti-corruption among the G20 countries. The group brings together the Supreme Audit Institutions (SAIs) of each participating country. The aim of the 2024 edition of the SAI will be to collaboratively explore, discuss and formulate a common perspective for SAIs on the issues of climate finance and poverty reduction.

Startup 20 was established in 2023 by the Indian presidency with the aim of promoting debate and the articulation of recommendations on the agendas of technology, innovation and the development of startups, small and medium-sized enterprises. The group brings together the leading names in the sector from all the countries in the group. The group's priorities are to discuss the sector's challenges, such as: technological transformations, public digital infrastructure, technologies as allies for preserving the environment, governance and multilateral reforms, as well as other essential themes for building a fairer and more sustainable future.

Parliament 20 (P20) or Parlamento 20 (in Portuguese) was established in 2010 by the Canadian presidency. The group is led by representatives of the parliaments of each G20 country and its meetings are primarily aimed at involving the parliamentary sphere in discussions on global governance, taking into account the political reality of each country. The P20 and the U20 are the only engagement groups whose main participants are government representatives.

The Civil 20 or Civil Society 20 (C20) was established in 2013 by the Russian presidency. The group is made up of representatives of organised civil society (e.g. NGOs, foundations, entities, social movements and others) in the G20. The Group was officially launched in 2013, although civil society engagement among G20 member countries began in 2010. The C20 provides a platform for Civil Society Organisations (CSOs) around the world to  provide space through which global CSOs can contribute in a structured and sustained way to the G20.

Ocean 20 (O20) or Oceano 20 (in Portuguese) was first organised in 2020 during Indonesia's presidency. The O20 has the aim of promoting debate and articulate recommendations on the ocean economy, preservation and conservation of the oceans. In the 2024 edition, the group is consolidated as part of the G20's official engagement groups in line with the global commitment to sustainable development.

Justice 20 (J20) was established in Buenos Aires in 2018 and is made up of representatives from the highest courts of the G20 countries. The J20 aims to be a global forum for bodies of constitutional jurisdiction, discussing current legal issues. Its agendas include topics such as human rights, sustainable development, strengthening the rule of law, judicial reforms and global justice. In addition, the J20 addresses specific themes such as climate litigation, the use of technology in judicial efficiency and the role of justice in promoting citizenship and social inclusion. These discussions reflect the search for global and collaborative solutions to complex legal and social issues.