  Galaxy clusters are biased tracers of the underlying matter density field. At
very large radii beyond about 10 Mpc/\textit{h}, the shear profile shows
evidence of a second-halo term. This is related to the correlated matter
distribution around galaxy clusters and proportional to the so-called halo
bias. We present an observational analysis of the halo bias-mass relation based
on the AMICO galaxy cluster catalog, comprising around 7000 candidates detected
in the third release of the KiDS survey. We split the cluster sample into 14
redshift-richness bins and derive the halo bias and the virial mass in each bin
by means of a stacked weak lensing analysis. The observed halo bias-mass
relation and the theoretical predictions based on the $\Lambda$CDM standard
cosmological model show an agreement within $2\sigma$. The mean measurements of
bias and mass over the full catalog give $M_{200c} = (4.9 \pm 0.3) \times
10^{13} M_{\odot}/\textit{h}$ and $b_h \sigma_8^2 = 1.2 \pm 0.1$. With the
additional prior of a bias-mass relation from numerical simulations, we
constrain the normalization of the power spectrum with a fixed matter density
$\Omega_m = 0.3$, finding $\sigma_8 = 0.63 \pm 0.10$.
