Later, Tamenobu captured the Namioka-jo Castle of Akimura KITABATAKE called 'Imperial Palace of Namioka', succeeded in taking control of the Tsugaru region and parts of Sotogahama and Mekanobu by around 1588, and in 1590 he took part in the conquest and siege of Odawara headed by Hideyoshi TOYOTOMI and had his territory approved by Hideyoshi.
その後、浪岡御所北畠顕村の浪岡城を攻め落とすなど、為信は天正16年（1588年）頃には津軽地方と外ヶ浜と糠部の一部を集中に収める事に成功し、天正18年（1590年）には豊臣秀吉の小田原征伐に参陣して、秀吉より所領を安堵された。