During the new product development (NPD) process, exploitation and exploration are important, especially for small manufacturing firms (SMFs). However, limited resources and a lack of internal knowledge capacity have forced SMFs to work with knowledge-intensive professional service firms (KIPSFs). This article investigates the impact of SMFs’ networks with KIPSFs on the performance of NPD. Using data from 164 SMFs in the northwest of England, this article reveals a linear relationship between firm's product innovativeness and its network with KIPSFs for exploitation, and a curvilinear relationship between firm's speed to market and its network with KIPSFs for exploration. A curvilinear relationship was also found between networks with KIPSFs for ambidexterity and firm's product innovativeness and speed to market. These results lead to several practical implications for networking strategy as each network supports different innovation activities and produces different outcomes.