In mathematics, an ordered semigroup is a semigroup together with a partial order that is compatible with the semigroup operation. Ordered semigroups have many applications in the theory of sequential machines, formal languages, computer arithmetics, and error-correcting codes. In 1999 Molodtsov [71] introduced the notion of a soft subset of a set as a new method for representing uncertainty that is free from the difficulties that have troubled the usual theoretical approaches. In this study, we applied soft set theory to ordered semigroups to obtain the notion of uni-soft left ideals, right ideals, bi-ideals, quasi-ideals, interior ideals and several properties are investigated. Moreover, uni-soft product and complement of soft characteristic function are introduced and the interrelations of them are presented. Characterizations of uni-soft left ideals, right ideals, bi-ideals, quasi-ideals, interior ideals are established. Using the notion of uni-soft left ideals, right ideals, bi-ideals, quasi-ideals, interior ideals, characterizations of semilattices of ordered semigroups are considered. Finally, the concept of uni-soft bi-ideal subsets, uni-soft filters and uni-soft bi-filters are defined and some characterizations of ordered semigroups are given.