  We propose a recursion relation for tree-level scattering amplitudes in
three-dimensional Chern-Simons-matter theories. The recursion relation involves
a complex deformation of momenta which generalizes the BCFW-deformation used in
higher dimensions. Using background field methods, we show that all tree-level
superamplitudes of the ABJM theory vanish for large deformations, establishing
the validity of the recursion formula. Furthermore, we use the recursion
relation to compute six-point and eight-point component amplitudes and match
them with independent computations based on Feynman diagrams or the
Grassmannian integral formula. As an application of the recursion relation, we
prove that all tree-level amplitudes of the ABJM theory have dual
superconformal symmetry. Using generalized unitarity methods, we extend this
symmetry to the cut-constructible parts of the loop amplitudes.
