The Euro 2012 co-hosts took the lead when Yarmolenko seized on goalkeeper Samir Handanovic's unconvincing punch.
Seleznyov slid in to convert the overlapping Artem Fedetskiy's cross after the break.
Josip Ilicic wasted a fine chance for Slovenia, but his side were fortunate not to fall further behind in the tie.
Seleznyov side-footed a tame shot against the post after Denys Garmash had directed a powerful header straight at Handanovic under little pressure.
Ukraine have lost in five previous qualifying play-offs for major tournaments - including a 3-2 aggregate reverse when they played Slovenia for a place at Euro 2000.
With former heavyweight boxing champion, now mayor of Kiev, Vitali Klitschko watching on in the stands, there seemed little chance of a repeat as Yarmolenko - the target of an unsuccessful bid by Premier League side Everton in August - and Yevhen Konoplyanka pulling the strings.
Despite a spell of late pressure, Slovenia, who picked up two of five yellow cards in a tetchy encounter, will have to show more adventure in the return in Maribor on Tuesday.
Match ends, Ukraine 2, Slovenia 0.
Second Half ends, Ukraine 2, Slovenia 0.
Corner,  Slovenia. Conceded by Yevhen Khacheridi.
Foul by Oleksandr Karavayev (Ukraine).
Bojan Jokic (Slovenia) wins a free kick on the left wing.
Substitution, Ukraine. Oleksandr Karavayev replaces Andriy Yarmolenko.
Substitution, Slovenia. Zlatan Ljubijankic replaces Milivoje Novakovic.
Attempt missed. Yevhen Konoplyanka (Ukraine) right footed shot from the centre of the box misses to the right. Assisted by Ruslan Malinovsky.
Foul by Ruslan Malinovsky (Ukraine).
Jasmin Kurtic (Slovenia) wins a free kick in the defensive half.
Yaroslav Rakitskiy (Ukraine) is shown the yellow card for a bad foul.
Foul by Yaroslav Rakitskiy (Ukraine).
Nejc Pecnik (Slovenia) wins a free kick in the attacking half.
Substitution, Ukraine. Artem Kravets replaces Evgen Seleznyov.
Attempt saved. Ruslan Malinovsky (Ukraine) left footed shot from outside the box is saved in the centre of the goal. Assisted by Andriy Yarmolenko.
Substitution, Ukraine. Ruslan Malinovsky replaces Denys Garmash.
Denys Garmash (Ukraine) wins a free kick in the defensive half.
Foul by Kevin Kampl (Slovenia).
Foul by Yevhen Khacheridi (Ukraine).
Nejc Pecnik (Slovenia) wins a free kick in the attacking half.
Foul by Yevhen Konoplyanka (Ukraine).
Branko Ilic (Slovenia) wins a free kick in the defensive half.
Attempt missed. Nejc Pecnik (Slovenia) left footed shot from the centre of the box is high and wide to the left. Assisted by Bojan Jokic with a cross.
Delay over. They are ready to continue.
Delay in match Denys Garmash (Ukraine) because of an injury.
Substitution, Slovenia. Nejc Pecnik replaces Valter Birsa.
Attempt missed. Yevhen Khacheridi (Ukraine) left footed shot from the centre of the box is too high following a corner.
Corner,  Ukraine. Conceded by Miso Brecko.
Yevhen Konoplyanka (Ukraine) wins a free kick in the defensive half.
Foul by Branko Ilic (Slovenia).
Corner,  Ukraine. Conceded by Bojan Jokic.
Evgen Seleznyov (Ukraine) hits the right post with a right footed shot from the left side of the box. Assisted by Andriy Pyatov.
Serhiy Rybalka (Ukraine) wins a free kick in the attacking half.
Foul by Jasmin Kurtic (Slovenia).
Denys Garmash (Ukraine) wins a free kick in the attacking half.
Foul by Rene Krhin (Slovenia).
Substitution, Slovenia. Roman Bezjak replaces Josip Ilicic.
Hand ball by Evgen Seleznyov (Ukraine).
Foul by Yaroslav Rakitskiy (Ukraine).
Josip Ilicic (Slovenia) wins a free kick in the attacking half.
Ukraine built a comfortable lead over Slovenia in their Euro 2016 play-off as Andriy Yarmolenko and Yevhen Seleznyov scored in a 2-0 win in Lviv.