|1933 Portsmouth Spartans season|
|Head coach||Potsy Clark|
|Home field||Universal Stadium|
|Division place||2nd NFL Western|
|Playoff finish||Did not qualify|
The 1933 Portsmouth Spartans season was their fourth in the league and final season before becoming the Detroit Lions. The team failed to improve on their previous season's output of 6–2–4, losing five games. They failed to qualify for the playoffs.
The Spartans started out fast with a 5–1 mark, just a half-game behind the first place Bears (5–0). After splitting their next two contests, Portsmouth (at 6–2) was still within half a game of Chicago (6–1–1). But the Spartans would lose their next three games, including back-to-back defeats to the Bears to close the season. The Spartans were sold and headed north for the 1934 season, becoming the Detroit Lions. Ironically, the team would return for one last game at Universal Stadium when the Lions' October 28 contest against failing Cincinnati Reds franchise was moved from the Queen City to Portsmouth; Detroit won, 38–0, in the last NFL game played in the small Ohio town.
|1||September 17||Cincinnati Reds||W 21–0||1–0||Universal Stadium||Recap|
|2||September 24||New York Giants||W 17–7||2–0||Universal Stadium||Recap|
|3||October 1||Chicago Cardinals||W 7–6||3–0||Universal Stadium||Recap|
|4||October 8||at Green Bay Packers||L 0–17||3–1||City Stadium||Recap|
|5||October 15||at Boston Redskins||W 13–0||4–1||Fenway Park||Recap|
|6||at Philadelphia Eagles||W 25–0||5–1||Baker Bowl||Recap|
|7||November 5||at New York Giants||L 10–13||5–2||Polo Grounds||Recap|
|8||November 12||Green Bay Packers||W 7–0||6–2||Universal Stadium||Recap|
|9||November 19||at Cincinnati Reds||L 7–10||6–3||Redland Field||Recap|
|10||November 26||at Chicago Bears||L 14–17||6–4||Wrigley Field||Recap|
|11||December 3||Chicago Bears||L 7–17||6–5||Universal Stadium||Recap|
Note: Intra-division opponents are in bold text.
|NFL Western Division|
|Green Bay Packers||5||7||1||.417||2–4||170||107||L1|
Note: Tie games were not officially counted in the standings until 1972.