This study investigates the geometric properties of almost \(\varvec{\eta }\) -Ricci-Bourguignon solitons on para-Kenmotsu manifolds. First, it is shown that if the metric \(\varvec{g}\) on a para-Kenmotsu manifold admits an almost \(\varvec{\eta }\) -Ricci-Bourguignon soliton and the Reeb vector field \(\varvec{\xi }\) preserves the function \(\varvec{\mu }\) , then the manifold \(\varvec{M}\) is Einstein. Next, we establish that if \(\varvec{g}\) is an almost \(\varvec{\eta }\) -Ricci-Bourguignon soliton and the vector field \(\varvec{\xi }\) leaves both \(\varvec{\lambda + \rho r}\) and \(\varvec{\mu }\) invariant, then the soliton reduces to an \(\varvec{\eta }\) -Ricci-Bourguignon soliton. Finally, we prove that if \(\varvec{g}\) is a gradient almost \(\varvec{\eta }\) -Ricci-Bourguignon soliton, then \(\varvec{M}\) is necessarily Einstein.