Building upon recent advances in GaSb-based diode lasers and Er-doped fluoride fibre technologies, this article demonstrates for the first time the fibre-based amplification of mid-infrared diode lasers in the wavelength range around 2.78 μm. The laser setup consists of a GaSb-based diode laser and a single-stage Er-doped fibre amplifier. Amplification is investigated for continuous wave (CW) and ns-pulsed input signals, generated by gain-modulation of the GaSb-based seed lasers. The experimental results include the demonstration of output powers up to 0.9 W, pulse durations as short as 20 ns, and pulse repetition rates up to 1 MHz. Additionally, the amplification of commercial and custom-made GaSb-based seed lasers is compared and the impact of different fibre end-cap materials on laser performance is analysed.