Boosted by a boisterous crowd of about 10,000 fans at the Islas Malvinas Stadium in the coastal city of Mar del Plata, the 11th-ranked Nalbandian dominated the match from the beginning, breaking Ferrer's service seven times. He closed the match by winning four of the last five games, clinching with an ace after 1 hour, 59 minutes.
Juan Martin del Potro, Argentina's highest ranked player, will face Feliciano Lopez in the second singles later Friday.
Playing in its first final at home, Argentina is seeking its first title after two runner-up finishes in 1981 and 2006. Spain, without top-ranked Rafael Nadal because of injury, is looking to win its third title.
Nalbandian had 54 winners and only 27 unforced errors on his way to victory, allowing only two breaks to Ferrer.
"I played a great match,'' Nalbandian said. "I couldn't have played it any better. It was good to win it fast. I was always ahead, that gave me tranquility.''
The Argentine got off to a fast start, breaking Ferrer in the third and seventh games to jump to a 5-2 lead. Ferrer responded with a break of his own to make it 5-3, but Nalbandian rebounded right away to secure the first set 6-3 after Ferrer's forehand went long.
Nalbandian kept the pace in the second set, breaking Ferrer three times, including in the final game after Ferrer missed wide on a crosscourt forehand.
In the final set, the Argentine broke Ferrer in the fourth game, cruising to victory with three aces in the last game to improve his career record against the 12th-ranked Ferrer to 4-6.
"It was a good first step for the weekend,'' Nalbandian said. "This 1-0 will help (Del Potro) play with less pressure.''
In his last four ATP events, Nalbandian won one title and reached two more finals. Ferrer had won his two Davis Cup singles this year.
"It's never an easy match against David,'' Ferrer said. "I felt inferior to him today. I thought I would challenge him more than I did.''
Spain is hoping to win its third title after home victories in 2000 and 2004. The Spaniards finished second in three other occasions - 1965, 1967 and 2003.
Argentina finished second to the United States in 1981 and to Russia in 2006. The Argentines are unbeaten in 13 home ties since 1998, when it lost to Slovakia. The home nation has a 16-11 record since the World Group was instituted in 1981.
The Argentines chose the blue indoor hard-court for the final trying to curtail the Spaniards' advantage on clay.
Nadal withdrew earlier this month after failing to recover from a knee injury, and captain Sanchez Vicario replaced him by 56th-ranked Marcel Granollers. The Davis Cup final has not had the participation of a No. 1 player since Australia's Lleyton Hewitt in 2001.
This is the third meeting between Argentina and Spain, with Spain winning the previous two on clay court in 1926 and 2003.
In Sunday's reverse singles, del Potro was drawn to play Ferrer and Nalbandian will face Lopez. For Saturday's doubles, Jose Acasuso and Agustin Calleri of Argentina have been paired against Lopez and Fernando Verdasco.
The United States won last year's final, beating Russia at home.
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