Longbottom transferred to Norman Low's Third Division Port Vale for a £2,000 fee in May 1961. He scored in his debut on 19 August, in a 4–2 defeat to Shrewsbury Town at Gay Meadow. He bagged 20 goals in 49 games in the 1961–62 season to become the club's joint-top-scorer (with Bert Llewellyn). He scored twice in 11 games in 1962–63, but new boss Freddie Steele sold him on to league rivals Millwall in January 1963 for a £2,000 fee. He scored one goal in ten league games for Ron Gray's "Lions", before leaving The Den in the summer.