The effect of B and P content on the amorphous forming ability (AFA), thermal stability, amorphous stability, and structural behavior was investigated in Fe-B-Nb-P alloys using metallic ribbons produced by a single-roller melt-spinning method. The maximum thickness, <inline-formula> <tex-math notation="LaTeX">t_{\mathbf {max}} </tex-math></inline-formula>, indicating AFA of Fe 84-{x} B 9 Nb 7 P x (<inline-formula> <tex-math notation="LaTeX">{x} =0 </tex-math></inline-formula>-4), increased from 19.5 to <inline-formula> <tex-math notation="LaTeX">68.7~\mu \text{m} </tex-math></inline-formula>. The alloys exhibited two exothermic peaks to have resulted from the formation of bcc <inline-formula> <tex-math notation="LaTeX">\alpha </tex-math></inline-formula>-Fe and borides, respectively. The Fe 84-{x} B 9 Nb 7 P x (<inline-formula> <tex-math notation="LaTeX">{x} =0 </tex-math></inline-formula>-3) alloys with the wide interval between two exothermic peaks exhibited the high thermal stability compared to the commercialized composition of Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 . The wide range between the glass transition temperature and crystallization temperature means the super-cooled liquid region, leading to obtain the high stable amorphous phase. The super-cooled liquid region was observed in Fe 81-{y} B 9+{y} Nb 7 P 3 (<inline-formula> <tex-math notation="LaTeX">{y} =0 </tex-math></inline-formula>-2) alloys and the endothermic reaction of the super-cooled liquid region got larger by increasing B content. The <inline-formula> <tex-math notation="LaTeX">\alpha </tex-math></inline-formula>-Mn type structure was observed in Fe 80 B 10 Nb 7 P 3 alloy annealed at 823 K, and it was considered to improve the amorphous stability. The Fe 81 B 9 Nb 7 P 3 alloy with a high AFA of <inline-formula> <tex-math notation="LaTeX">68.7~\mu </tex-math></inline-formula> m exhibited excellent magnetic characteristics, <inline-formula> <tex-math notation="LaTeX">B_{s} </tex-math></inline-formula> of 1.51 T and <inline-formula> <tex-math notation="LaTeX">H_{c} </tex-math></inline-formula> of 4.7 A/m.