BaMoO4: Er3+/Yb3+ phosphors with different concentrations have been fabricated by a facile hydrothermal method. The morphology observation shows that the shape and size of BaMoO4 powders change after Er3+/Yb3+ doping. The upconversion luminescence spectra consist of intense green bands centered at 536 and 558 nm and a weak red emission band peaked at 668 nm upon 980 nm excitation. The excitation power and doping concentration have little impacts on the color emitted from the samples. Applying the fluorescence intensity ratio (FIR) technique, the temperature sensing behaviors are investigated based on thermally coupled levels (2H11/2 and 4S3/2) and non-thermally coupled levels (4F9/2 and 4S3/2), respectively. The thermometry is sensitive to the excitation power for 4F9/2 and 4S3/2 levels, leading to large measurement errors caused by the power variation. Such a problem can be solved by using the power-insensitive FIR between 2H11/2 and 4S3/2 levels, which also shows the advantage of high absolute sensitivity with the maximum of 110.7 × 10−4 K−1. So, the developed BaMoO4:Er3+/Yb3+ phosphors can be applied in green light upconverters, display devices and temperature sensors.