Jonny Bairstow top scored with 60 not out and Alex Hales was unbeaten on 47 as England reached their target of 142 with 5.5 overs to spare.
The second match of the series is in Taunton on Friday.
South Africa eliminated from the group stage of Champions Trophy 2017 after defeated by India.
England are now No. 3 in the ICC's rankings of IT20 teams, with South Africa ranked No. 6.
On choosing to bat, South Africa captain De Villiers predicted that the Southampton surface could be on the slow side, but the Proteas' struggle to score was down to the skill of the home attack.
Tied down in the middle overs by Hampshire spin twins Mason Crane - making his global bow - and Liam Dawson, the right- and left-arm duo worked well in tandem to restrict the batsmen, giving away few bad balls in their combined eight overs, going for only 41 runs between them.
Wayne Parnell conceded 25 runs off two overs, bowling down leg, insufferably short and then too wide.
Crane, compared in these parts to the Australian great and Hampshire icon Shane Warne, bowled just one bad ball on debut, finishing with a full toss that De Villiers crunched for four.
If South Africa failed to get to grips with the conditions, England made Southampton look ideal for batting and cantered the chase.
After managing just 51 runs in eight one-day global innings so far this season, Roy made 92 for Surrey in their One-Day Cup semi-final win over Worcestershire last week.
But on 28 he missed an ambitious reverse-sweep against medium-pacer Andile Phehlukwayo and was plumb lbw. Two balls later, a drop-and-run for a single ended what was barely a contest.
However, its manner and the fact it came on the back of more runs from the in-form Jonny Bairstow bodes well for the rest of the summer. "It is important for the ICC (International Cricket Council) and these franchise events to get the right balance in the future for the players to know where they are going with their career", said de Villiers. I have always been the person to try and see the positive and the opportunity to improve, these three matches give me that opportunity as a player and as captain of the team.
"The lads bowled outstandingly well. The lads bowled outstanding well, taking wickets up front and then the spinners tied them down".
However his form took a turn for the worse as he endured a hard time in ODI series against the West Indies, Ireland and South Africa.
"I'm feeling good, I was really pleased". I reckon 20 or 30 more woulkd have been a good total - we lost our way in the first six and had to rebuild a bit.
Police sources confirmed the incident and told she was hanging from the ceiling fan at her Andheri apartment in Mumbai . Moments after the police were called; Srivastava was rushed to the Cooper hospital where she was declared dead.
Because of that, Trump has restored some, but not all, of the economic and travel restrictions in place before Obama's action. He added that Trump's decision "is about USA national interests but also about the interests of humanity - these poor people".
The council is made up of CEOs from Silicon Valley's most prominent companies, as well as over a dozen White House officials. The White House on Monday urged technology CEOs to pitch in on President Donald Trump's effort to modernize government.
After the 2010 census produced new population estimates the GOP-controlled state assembly redrew the district lines. Democrats do likewise where they control the line-drawing process, such as in Illinois, Maryland and MA .
A silent auction starts at 5 p.m. featuring a wide variety of items donated by area businesses and Relay For Life team members. Sobel has volunteered with the American Cancer Society for almost 20 years since the start of the Relay for Life in Wilton.
He told the Spanish media after scoring in Spain's 2-1 World Cup qualifying win over Macedonia: "Things don't work like that". Despite all his problems with discipline, I believe Wenger can manage that as he's done with numerous players over the years.
He is slated to take part in next week's Australian Open, where he is drawn to face Sakai in the first round of the qualifiers. Son moved to a 13-10 lead after the interval but Srikanth slowly levelled par at 14-14 with a clever shot on Sons forehand.
Forecasts said the system could dump from a few inches to more than 12 inches, depending on Cindy's development and path. Its maximum sustained winds are near 40 miles per hour (64 kph) with weakening expected to begin later in the day.
Today, Indian missions in France, the US, Switzerland, Uganda, Kenya, Australia organised yoga sessions, ahead of the IYD. Over 190 countries, including 40 Islamic nations, supported the move to have a special day for yoga.
Celtic will not play Linfield in Belfast on July 12
The former Rangers striker said: " Celtic are a ruthless outfit who find chinks in the opposition's armour and expose them". A side from San Marino is all that stands between Celtic and a very interesting trip to Belfast.
Lions back three places not decided - Gatland
He frequently kept the point of attack shifting and worked well running off the back of scrums and as the link man in phase play. The Chiefs have at least 11 players out of this one, either in the All Blacks squad or not able to back up from the Maori game.
Too hot to handle: Study shows Earth's killer heat worsens
Currently, about 30 percent of the world's human population is exposed to deadly heatwave conditions each year, Mora said. The increase in deadly heat days for various cities can be seen in an interactive map the researchers put together.
Congressman, others wounded in shooting in Va.
Republicans and Democrats put aside their differences to root for "Team Scalise" during the Congressional Baseball Game this year. The game at Nationals Park carried on a century-old bipartisan ritual, this one tinged with worry about Louisiana Rep.
Ohio man charged in 2 killings is charged in 3 more slayings
The Stark County Sheriff's Office said it has secured arrest warrants for Brinkman for two counts of murder for the Johns' deaths. When he noticed that the doorknob leading into their bedroom was broken, and the dog barking, he knew there was something wrong.
USA shoots down Syrian fighter jet over Syria
The U.S. -led coalition, which has in recent weeks escalated its aerial bombing campaign in northern Syria and Raqqa province. The Pentagon said Sunday a Syrian SU-22 dropped bombs on coalition-partnered fighters near the town of Tabqah.
Ward Stops Kovalev to Retain Light Heavyweight Crown
In his post-fight interview, Kovalev questioned the intervention of Weeks and suggested that he had received an illegal punch. Kovalev did a better job fighting on the inside and equaling Ward's physicality from the clinch during the rematch.
Hosts Russia Ease Past New Zealand In Confed Cup Opener
But Wood - and coach Anthony Hudson - maintain their belief that something special is brewing inside the New Zealand camp. Michael Boxall , left, and Tommy Smith are too late to prevent Russian Federation taking a lead in the first half.
Oil falls to $46, Nigerian cargoes face competition
Crude output from OPEC nations rose by 290,000 bpd in May to a 2017 high of 32.08 million barrels per day, according to the EIA . The IEA expects oil supplies next year to outpace demand despite consumption hitting 100 million bpd for the first time.