To minimize pyroelectric effects while keeping high piezoelectric effects in relaxor-PbTiO 3 single crystals, the crystallographic orientation dependence of the pyroelectric and piezoelectric coefficients were investigated for binary (1 − x)Pb(Mg 1/3 Nb 2/3 )O 3 –xPbTiO 3 (PMN–PT), ternary (1 − x − y)Pb(In 1/2 Nb 1/2 )O 3 –yPb(Mg 1/3 Nb 2/3 )O 3 –xPbTiO 3 (PIN–PMN–PT) and Mn-doped PIN–PMN–PT single crystals with the “4R” multidomain state. The secondary pyroelectric coefficients were calculated from the thermodynamic inter-relationship between the piezoelectric, elastic, and thermal expansion coefficients, being on the order of (1.16–1.23) × 10 −4 C m −2 K −1 for binary crystals and (0.97–2.03) × 10 −4 C m −2 K −1 for ternary ones. The primary pyroelectric coefficients were –(6.73–6.84) × 10 −4 C m −2 K −1 and −(5.44–6.43) × 10 −4 C m −2 K −1 for binary and ternary crystals, respectively. The pyroelectric coefficients could be reduced by matrix rotation, but at the cost of decreasing longitudinal piezoelectric coefficients d 33 . Of particular interest is that the maximum piezoelectric coefficients d24∗ at θ = ±55 o and d34∗ at θ = ±35 o by a counterclockwise rotation of θ about the X axis (θ is the rotation angle about the coordinate axes), or d15∗ at θ = ±55 o , and d35∗ at θ = ±35 o by a counterclockwise rotation the Y axis, were found on the order of 3000 pC N −1 . The corresponding pyroelectric coefficients could be reduced by ∼20%. The reduced pyroelectric coefficients that can contribute to decrease undesirable output signals, together with the high piezoelectric coefficients, enable relaxor-PT crystals as favorable candidates for high-sensitivity piezoelectric sensors.