The transcription factor Foxp3 is essential for the development of functional, natural Treg (nTreg), which plays a prominent role in self‐tolerance. Suppressive Foxp3⁺ Treg cells can be generated from naïve T cells ex vivo, following TCR and TGF‐β1 stimulations. However, the molecular contributions from the different arms of these pathways leading to Foxp3 expression are not fully understood. TGF‐β1‐activated Smad3 plays a major role in the expression of Foxp3, since TGF‐β1‐induced‐Treg generation from Smad3^−/− mice is markedly reduced and abolished by inactivating Smad2. In the TCR pathway, deletion of Bcl10, which activates NF‐κB, markedly reduces both IL‐2 and Foxp3 production. However, partial rescue of Foxp3 expression occurs on addition of exogenous IL‐2. TGF‐β1 significantly attenuates NF‐κB binding to the Foxp3 promoter, while inducing Foxp3 expression. Furthermore, deletion of p50, a NF‐κB subunit, results in increased Foxp3 expression despite a decline in the IL‐2 production. We posit several TCR‐NF‐κB pathways, some increasing (Bcl10‐IL‐2‐Foxp3) while others decreasing (p50‐Foxp3) Foxp3 expression, with the former predominating. A better understanding of Foxp3 regulation could be useful in dissecting the cause of Treg dysfunction in several autoimmune diseases and for generating more potent TGF‐β1‐induced‐Treg cells for therapeutic purposes.