The Blitzboks and Fiji entered the final level on log points, and tries on either side of the break gave the South Africans a 10-0 lead that ultimately set them on course for the series title.
Fiji pulled one back later in the half, but outstanding defence in their own territory ensured the South Africans held firm.
There was drama right until the end. Fiji launched one final attack in the closing 30 seconds, but a knock-on with the tryline beckoning handed possession back to the Blitzboks. From the resulting scrum Fiji conceded a penalty, and much to the relief of the green-and-gold supporters, the ball was kicked into touch.
The opening try came from a defensive turnover. Impi Visser ripped the ball free in a tackle and, after some slick passing, Gino Cupido raced in after just two minutes for the only score of the first half.
The second half proved just as tight, with razor-thin margins deciding the outcome. Tristan Leyds struck two minutes after the restart when Fiji lost the ball in a tackle near their line, giving the Blitzboks a two-score cushion with five minutes remaining.
But Fiji's reputation as comeback specialists nearly surfaced again. Terio Veilawa scored and converted soon afterwards to cut the deficit to three points, setting up a tense finish.
The decisive equaliser never came, however, thanks largely to gritty Blitzbok defence that forced crucial errors, while smart game management kept Fiji at bay.
The Blitzboks - who also won tournaments in Cape Town, Perth and Vancouver - underlined their dominance as the standout team in the HSBC SVNS Series.
Earlier on Sunday, they booked their place in the final with a hard-fought 14-5 semi-final victory over Argentina, scoring twice in the first half before defending resolutely.
Sebastiaan Jobb opened the scoring in the second minute after a swift transition from defence to attack. Argentina pressed hard but could not breach the South African line, eventually throwing a stray pass.
The turnover involved Visser and Leyds, and once Jobb received the ball there was only one outcome. Leyds added the conversion to make it 7-0.
A 70-metre run from Selvyn Davids produced the next try and a 14-0 halftime lead.
Argentina struck early in the second half when Marcos Moneta finished in the corner two minutes after the restart to reduce the deficit to 14-5.
The final five minutes were frantic, featuring a flurry of penalties, turnovers and a disallowed Springbok Sevens try, but the Blitzboks held on to secure victory.
Springbok Sevens coach Philip Snyman cut an emotional figure following a gutsy 10-7 victory over Fiji in the final of the HSBC SVNS New York on Sunday, a win which secured them the World Series crown.
The race for the SVNS Series title will go down to the wire on the second day of the HSBC SVNS New York tournament on Sunday, with the Springbok Sevens and Fiji still locked in a battle for top honours.
Springbok Sevens forward David Brits says the hard work done in the set piece is just as rewarding as scoring the spectacular tries that often follow.
The Springbok Sevens arrived on the east coast of the United States of America on Monday afternoon with their eyes firmly HSBC SVNS World Series title.
