This volume contains the proceedings of the ICM 2018 satellite school and workshop $K$-theory conference in Argentina. The school was held from July 16-20, 2018, in La Plata, Argentina, and the workshop was held from July 23-27, 2018, in Buenos Aires, Argentina. The volume showcases current developments in $K$-theory and related areas, including motives, homological algebra, index theory, operator algebras, and their applications and connections. Papers cover topics such as $K$-theory of group rings, Witt groups of real algebraic varieties, coarse homology theories, topological cyclic homology, negative $K$-groups of monoid algebras, Milnor $K$-theory and regulators, noncommutative motives, the classification of $C^*$-algebras via Kasparov's $K$-theory, the comparison between full and reduced $C^*$-crossed products, and a proof of Bott periodicity using almost commuting matrices.