© 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The micro-transfer-printing of prefabricated C-band semiconductor optical amplifiers (SOAs) on a silicon waveguide circuit is reported. The SOAs are 1.35 mm in length and 40 µm in width. Dense arrays of III-V SOAs are fabricated on the source InP wafer. These can then be micro-transfer-printed on the target SOI photonic circuits in a massively parallel fashion. Additionally, this approach allows for greater flexibility in terms of integrating different epitaxial layer structures on the same SOI waveguide circuit. The technique allows integrating SOAs on a complex silicon photonic circuit platform without changing the foundry process-flow. Two different SOA designs with different optical confinement factor in the quantum wells of the III-V waveguide are discussed. This allows tuning the small-signal gain and output saturation power of the SOA. The design with higher optical confinement in the quantum wells has a small-signal gain of up to 23 dB and an on-chip saturation power of 9.2 mW at 140 mA bias current and the lower optical confinement factor design has a small-signal gain of 17 dB and power saturation of 15 mW at 160 mA of bias current.