Let N be a zero-symmetric (right) nearring with identity. We introduce a partial order in the matrix nearring corresponding to the partial order (defined by Pilz in Near-rings: the theory and its applications, North Holland, Amsterdam, 1983) in N. A positive cone in a matrix nearring is defined and a characterization theorem is obtained. For a convex ideal I in N, we prove that the corresponding ideal $${I^*}$$
I
∗
is convex in $$M_n(N)$$
M
n
(
N
)
, and conversely, if I is convex in $$M_n(N)$$
M
n
(
N
)
, then $${I_{*}}$$
I
∗
is convex in N. Consequently, we establish an order-preserving isomorphism between the p.o. quotient matrix nearrings $$M_n(N)/{I^*}$$
M
n
(
N
)
/
I
∗
and $$M_n(N')/{(I')^*}$$
M
n
(
N
′
)
/
(
I
′
)
∗
where I and $$I'$$
I
′
are the convex ideals of p.o. nearrings N and $$N'$$
N
′
, respectively. Finally, we prove some properties of Archimedean ordering in matrix nearrings corresponding to those in nearrings.