The canton of Saint-Malo-Sud is a former canton of France, located in the arrondissement of Saint-Malo, in the Ille-et-Vilaine département, Brittany région. It had 23,198 inhabitants (2012). It was disbanded following the French canton reorganisation which came into effect in March 2015.

The canton comprised the following communes:

• La Gouesnière ;
• Saint-Jouan-des-Guérets ;
• Saint-Malo (fraction).

At the 2011 cantonal elections, UMP councillor Gilles Lurton was elected to represent the canton of Saint-Malo-Sud in the general council of Ille-et-Vilaine department.

Cantonal Elections 2004: Saint-Malo-Sud

Party		Candidate	Votes	%	±%
	PS	Le Menn	4,239	33.76
	UMP	Lurton	4,958	39.48
	LV	Le Brelot	1,121	8.93
	FN	Beaujean	921	7.33
	LCR	Pierre Chapa	519	4.13
	PRG	Gaillard	308	2.45
	Far left	Floriat	251	2.00
	PCF	Le Sager	241	1.92
Turnout			12 558	61.57
	PS	Le Menn	5,787	50.83
	UMP	Lurton	5,599	49.17
Turnout			11,386	55.75
	PS hold		Swing

Cantonal Elections 1998: Saint-Malo-Sud

Party		Candidate	Votes	%	±%
	PS	Le Menn	2,711	28.97
	UDF	Lurton	2,452	26.20
	DVD	Goger	2,159	23.07
	FN	Mary	727	7.77
	UDB	Henri Gourmelen	489	5.23
	PCF	Le Sager	391	4.18
	Far left	Groisier	211	2.25
	Far right	Cazal	190	2.03
	Miscellaneous	Dehergne	28	0.30
Turnout			9,358	54.74
	PS	Le Menn	4,261	50.22
	UDF	Lurton	4,223	49.78
Turnout			8,981	50.07
	PS gain from DVD		Swing

48°37′04″N 1°57′27″W / 48.61778°N 1.95750°W / 48.61778; -1.95750