| Margaret Jeffery | |
| Fullname: | Margaret Kathleen Jeffery |
| Strokes: | Freestyle |
| Birth Date: | 23 January 1920 |
| Birth Place: | Bromely, Surrey, England |
| Death Place: | Kings Lynn, Norfolk, England |
Margaret Kathleen Jeffery (23 January 1920 - 12 September 2004) was an English freestyle swimmer of the 1930s, who represented Great Britain in the Olympics and competed for England in the British Empire Games.
At the 1936 Summer Olympics in Berlin, she was a member of the British women's that came sixth in the 4×100-metre freestyle relay. In the 400-metre freestyle she was eliminated in the semi-finals. At the 1938 Empire Games in Sydney, Australia, she won the silver medal in the 440-yard freestyle contest.