  This study investigates the stability of higher-dimensional singly rotating
Myers-Perry-de Sitter (MP-dS) black holes against scalar field perturbations.
The phase spaces of MP-dS black holes with one spin parameter are discussed.
Additionally, the quasinormal modes (QNMs) of MP-dS black holes are calculated
via the asymptotic iteration method and sixth-order Wentzel-Kramers-Brillouin
approximation. For near-extremal MP-dS black holes, the event horizon may be
considerably close to the cosmological horizon. In such cases, the
P\"oschl-Teller technique yields an accurate analytic formula for the QNMs. It
is found that when the spin parameter of a black hole increases, the scalar
perturbation modes oscillate at higher frequencies and decay faster.
Furthermore, the MP-dS black hole with a single rotation is found to be stable
under perturbation.
