Let p be a prime, and let \(\mathbb {F}_q\) denote the finite field of order \(q = p^m\) where \(m \ge 2\) . Firstly, we introduce and analyze the algebraic structures of skew polycyclic codes over the ring \(R = \mathbb {F}_q + v\mathbb {F}_q\) , where \(v^2 = v\) . Then, we investigate skew polycyclic codes of length \(\alpha +\beta \) over \(\mathbb {F}_q R\) as a generalization of skew polycyclic codes over R. Subsequently, we study the algebraic structures of these codes by determining their generator polynomials and minimal generating sets. Furthermore, we establish the structure of the dual codes corresponding to \((\theta , \Theta )\) -cyclic codes, which constitute a special class of skew polycyclic codes. As an application of our study, several optimal linear codes over \(\mathbb {F}_{q}\) are provided.