In this paper, we propose a novel way to construct off-shell actions of Carrollian field theories by restricting the Bargmann invariant field theories on the null hyper-surface. We focus on free scalar field theory and electromagnetic field theory, and show that the electric and magnetic sectors of these theories can be reduced from different Bargmann invariant actions in one higher dimension. For the massless free scalar and d = 4 electromagnetic field, the constructed Carrollian theories are furthermore Carrollian conformal invariant.We compute the 2-point correlators in these theories, and show that they satisfy the Ward identities of Carrollian conformal symmetry. We find that there appear naturally the chain representation, the net representation and the staggered module of Carrollian conformal algebra in the constructed Carrollian conformal invariant theories.