Both tissue engineering and biological science will benefit from improved methods to control the morphology, differentiated state, and function of primary cells. In this paper, we show that surface modification of tissue culture polystyrene (TCPS) with chemically derivatized elastin-like polypeptides (ELPs) enables control over the in vitro morphology and liver-specific function of primary rat hepatocytes. The ELP (VPGVG)40 was produced in Escherichia coli and conjugated with polyacrylic acid (PAA) and polyethyleneimine (PEI) using carbodiimide activation chemistry. These conjugates were characterized by transmission Fourier transform infrared (FTIR) spectroscopy, mass spectroscopy, and the ninhydrin assay. We demonstrated that the ELP-polyelectrolyte conjugates profoundly influenced the morphology, aggregation, and differentiated function of primary rat hepatocytes, where hepatocytes plated on the ELP-PAA and ELP-PEI surfaces formed spread and spheroidal morphologies with corresponding low and high liver-specific function, respectively. These materials may have utility as substrata for in vitro studies of hepatocyte biology and tissue engineering applications.