Singles
2018 Seoul Open Challenger
Champion	Mackenzie McDonald
Runner-up	Jordan Thompson
Score	1–6, 6–4, 6–1

Thomas Fabbiano was the defending champion but chose not to defend his title.

Mackenzie McDonald won the title after defeating Jordan Thompson 1–6, 6–4, 6–1 in the final.

Seeds

Draw

Finals

	Semifinals							Final
		Jason Kubler	3	6	4
	3	Jordan Thompson	6	3	6
								3	Jordan Thompson	6	4	1
								5	Mackenzie McDonald	1	6	6
	5	Mackenzie McDonald	6	77
	8	Tatsuma Ito	4	64

Top half

	First round							Second round							Quarterfinals							Semifinals
	1	V Pospisil	4	6	6
		B Schnur	6	1	3			1	V Pospisil	3	3
		J Kubler	6	6					J Kubler	6	6
		Ze Zhang	1	1												J Kubler	6	6
		S-w Kwon	6	1	6											S-w Kwon	3	4
		M Janvier	1	6	3				S-w Kwon	6	6
		M Giron	6	3	4			6	G Soeda	4	4
	6	G Soeda	1	6	6																		J Kubler	3	6	4
	3	J Thompson	6	6																		3	J Thompson	6	3	6
	WC	Kim Young-seok	1	2				3	J Thompson	7	711
		F Peliwo	7	3	1r			Q	J-h Son	5	69
	Q	Son Ji-hoon	5	6	3										3	J Thompson	6	6
	Q	Renta Tokuda	1	2												T-h Yang	1	3
		T-h Yang	6	6					T-h Yang	6	7
	Q	Makoto Ochi	4	0				7	J Jung	4	5
	7	J Jung	6	6

Bottom half

	First round							Second round							Quarterfinals							Semifinals
	5	M McDonald	7	6
	WC	U-s Park	5	2				5	M McDonald	6	6
	SE	K Majchrzak	6	6				SE	K Majchrzak	3	4
		Y Takahashi	2	3											5	M McDonald	64	710	6
		L Harris	5	6	6											L Harris	77	68	3
	WC	Y-s Chung	7	3	0				L Harris	6	3
		M Banes	4	1				4	Y-h Lu	4	0r
	4	Y-h Lu	6	6																		5	M McDonald	6	77
	8	T Ito	6	6																		8	T Ito	4	64
		D-h Lee	1	3				8	T Ito	7	6
		Y Uchiyama	6	4	5			WC	S-c Hong	5	1
	WC	S-c Hong	2	6	7										8	T Ito	7	3	6
	Q	Yo Watanuki	6	6												D Wu	5	6	2
		D Kelly	3	4				Q	Yo Watanuki	4	5
		D Wu	6	2	6				D Wu	6	7
	2	D Sela	3	6	0

References

• Main Draw
• Qualifying Draw