0001979330 2025-01-28 2025-01-28 false 333-272567 0001979330 617 387-1110 NASDAQ 8-K 2025-01-28 NB Bancorp, Inc. MD 93-2560883 1063 Great Plain Avenue Needham MA 02492 false false false false Common Stock, Par Value $0.01 Per Share NBBK true false