The 37-year-old from Carrickfergus has won 17 races on the 8.9-mile Northern Ireland road circuit and goes for more glory on Thursday and Saturday.
Thursday's final qualifying session was halted because of an accident involving English rider John McGuinness.
The 45-year-old sustained a suspected broken leg, race organisers said.
Last year Seeley won both Supersport races and he was top of the podium in North West three events in in 2012 and 2015.
His first NW200 was in 2008 and last year he beat the 15 wins achieved by the late Robert Dunlop.
Michael Rutter showed he is in the form to add to his 13 North West 200 wins by taking pole position in the Superbike class.
The 45-year-old's last NW success was in 2012.
Seeley was second in the Superbikes ahead of Northern Ireland riders Glenn Irwin and Michael Dunlop.
THURSDAY'S VAUXHALL NORTH WEST 200 PRACTICE TIMES
Record holder Alastair Seeley will be on pole position in the Supersport and Superstock races when he tries to add to his tally of North West 200 wins.