The ABC spectral radius of a graph G is the largest eigenvalue of the
ABC matrix modified from the adjacency matrix of G so that the
for an edge uv, where dw is the degree of vertex w in G.
We show that the graph formed from a cycle of length n-p by attaching p
pendent edges to a vertex uniquely maximizes the ABC spectral radius
over all n-vertex unicyclic graphs with p pendant edges, and over all
n-vertex unicyclic graphs with girth n-p, respectively.