A measurement of the $ B_{s}^{0} \rightarrow J/\psi \phi $ decay parameters using $ 80.5\, \mathrm {fb^{-1}} $ of integrated luminosity collected with the ATLAS detector from 13 $\text {Te}\text {V}$ proton–proton collisions at the LHC is presented. The measured parameters include the CP-violating phase $\phi _{s} $, the width difference $ \Delta \Gamma _{s}$ between the $B_{s}^{0}$ meson mass eigenstates and the average decay width $ \Gamma _{s}$. The values measured for the physical parameters are combined with those from $ 19.2\, \mathrm {fb^{-1}} $ of 7 and 8 $\text {Te}\text {V}$ data, leading to the following: $\begin{aligned} \phi _{s}= & {} -0.087 \pm 0.036 ~\mathrm {(stat.)} \pm 0.021 ~\mathrm {(syst.)~rad} \\ \Delta \Gamma _{s}= & {} 0.0657 \pm 0.0043 ~\mathrm {(stat.)}\pm 0.0037 ~\mathrm {(syst.)~ps}^{-1} \\ \Gamma _{s}= & {} 0.6703 \pm 0.0014 ~\mathrm {(stat.)}\pm 0.0018 ~\mathrm {(syst.)~ps}^{-1} \end{aligned}$Results for $\phi _{s} $ and $ \Delta \Gamma _{s}$ are also presented as 68% confidence level contours in the $\phi _{s} $–$ \Delta \Gamma _{s}$ plane. Furthermore the transversity amplitudes and corresponding strong phases are measured. $\phi _{s} $ and $ \Delta \Gamma _{s}$ measurements are in agreement with the Standard Model predictions.