We first introduce the concept of an alpha-{psi(k)}(1)(n)-admissible mapping which generalizes the notion of alpha-admissible mapping and establish the existence and uniqueness of fixed points for such mappings in complete metric spaces as well as in partially ordered metric spaces. The presented theorems generalize and improve many existing results in the literature. Moreover, some examples and an application to integral equations are provided to illustrate the usability of the obtained results.