Near-infrared (NIR) luminescent lanthanide(III) (Ln3+) metal–organic frameworks (MOFs) constitute a class of materials possessing unique advantages for a wide range of applications due to their photophysical and structural properties. In this work, we present the synthesis and characterization of two series of Ln3+-based MOFs emitting in the NIR region (Ln-MOFs) constructed using 2,6-naphthalene dicarboxylic acid (H2NDC) and its two amino derivatives, 4-aminonaphthalene-2,6-dicarboxylic acid (H2ANDC) and 4,8-diaminonaphthalene-2,6-dicarboxylic acid (H2DANDC). The first series comprises mixed-ligand and mixed-metal MOFs with the general formula [La1−xLnx(NDC)1−y(ANDC)yCl(DMF)] (Ln = Nd3+, Yb3+, x = 0.005–1, y = 0–0.2), while the second series features MOFs corresponding to the formulae [La1−xLnx((NDC)1−y(ANDC)y)1.5(DMF)2]·DMF (Ln = Nd3+, Er3+, Yb3+, Lu3+, x = 0.1 or 1, y = 0.45 or 1) and [Ln(DANDC)1.5(DMF)2]·DMF (Ln = Nd3+, Er3+, Yb3+). Detailed studies of the photophysical properties of Ln-MOFs have demonstrated that MOF scaffolds provide an efficient sensitization of NIR-emitting Ln3+ ions (ηsens up to 38% for Nd3+ analogues). In addition, Ln-MOFs possess long Ln3+ luminescence lifetimes (up to 12 μs for Yb3+ analogues) and exhibit Ln3+ luminescence quantum yields comparable with the highest values reported today for NIR-emitting Ln-MOFs. We discuss and compare the photophysical processes that lead to Ln3+ sensitization in two series of Ln-MOFs. Most importantly, the studied Ln-MOFs are among the few examples of Ln3+-based NIR-emitting MOFs where Ln3+ emission can be sensitized upon excitation in the visible range (up to 450 nm).