In this paper, we present the monotonicity analysis for the nabla fractional differences with discrete generalized Mittag-Leffler kernels $( {}^{ABR}_{a-1}{\nabla }^{\delta ,\gamma }y )(\eta )$
(
a
−
1
A
B
R
∇
δ
,
γ
y
)
(
η
)
of order $0<\delta <0.5$
0
<
δ
<
0.5
, $\beta =1$
β
=
1
, $0<\gamma \leq 1$
0
<
γ
≤
1
starting at $a-1$
a
−
1
. If $({}^{ABR}_{a-1}{\nabla }^{\delta ,\gamma }y ) ( \eta )\geq 0$
(
a
−
1
A
B
R
∇
δ
,
γ
y
)
(
η
)
≥
0
, then we deduce that $y(\eta )$
y
(
η
)
is $\delta ^{2}\gamma $
δ
2
γ
-increasing. That is, $y(\eta +1)\geq \delta ^{2} \gamma y(\eta )$
y
(
η
+
1
)
≥
δ
2
γ
y
(
η
)
for each $\eta \in \mathcal{N}_{a}:=\{a,a+1,\ldots\}$
η
∈
N
a
:
=
{
a
,
a
+
1
,
…
}
. Conversely, if $y(\eta )$
y
(
η
)
is increasing with $y(a)\geq 0$
y
(
a
)
≥
0
, then we deduce that $({}^{ABR}_{a-1}{\nabla }^{\delta ,\gamma }y )(\eta ) \geq 0$
(
a
−
1
A
B
R
∇
δ
,
γ
y
)
(
η
)
≥
0
. Furthermore, the monotonicity properties of the Caputo and right fractional differences are concluded to. Finally, we find a fractional difference version of the mean value theorem as an application of our results. One can see that our results cover some existing results in the literature.