In this paper, we focus on the optimal beamformer design for rate splitting multiple access (RSMA)-aided multipleinput single-output (MISO) visible light communication (VLC) networks. First, we derive the closed-form lower bounds of the achievable rate of each user, which are the first theoretical bound of achievable rate for RSMA-aided VLC networks. Second, we investigate the optimal beamformer design for RSMA-aided VLC networks to maximize the sum rate under the optical and electrical power constraints. In addition, we show that the proposed RSMA-aided networks can achieve superior performance compared with space-division multiple access (SDMA) and nonorthogonal multiple access (NOMA).