  Magnetotransport such as the giant magnetoresistance and Hall effect lies at
the heart of fundamental physics and technologies. Recently, some experiments
have clearly demonstrated linear magnetotransport (LMT) proportional to
magnetic field but the underlying physical mechanism is still unclear. In this
work, we show that Berry curvature effect is a new mechanism dominating the
LMT. The Berry-curvature-induced LMT widely exists in 66 out of 122 magnetic
point groups. For typical magnetic Weyl semimetals Co$_3$Sn$_2$S$_2$ and
ferromagnetic MnBi$_2$Te$_4$, Berry curvature induces LMT conductivities
reaching orders of $10^4$ and $10^2$ ${\rm \Omega^{-1}m^{-1}}$ per tesla,
respectively, which are tunable through magnetization canting induced by
moderate magnetic fields. We further reveal that Berry-curvature-induced LMT
can be detected by Hall effect and especially intrinsic magnetoresistance
exceeding $100\%$ per tesla insensitive to the sample quality. Our results
agree with recent experiments and uncover the important role of Berry curvature
in LMT.
