Angel Rangel opened the scoring when his shot squirmed under the body of goalkeeper Jussi Jaaskelainen.
James Collins gifted Swansea a second when his back pass fell short and let in Michu to score.
Play media
Laudrup thrilled with start
West Ham offered little and Danny Graham finished off a fine move with a third in the second half.
Michael Laudrup's side were well worth their victory, which took them to the top of the Premier League having scored eight goals in their opening two games.
Scott Sinclair was not in the matchday squad with Swansea reported to have accepted a bid from Manchester City for the winger.
Record signing Ki Sung-Yueng was not eligible for the game but the South Korean international was introduced to the Liberty Stadium crowd before kick-off.
West Ham started with new £10m recruit Matt Jarvis, one of two changes, along with James Tomkins, to the side that defeated Aston Villa last weekend.
Jarvis was prominent as the visitors started well, but captain Kevin Nolan failed to get on the end of the former Wolves winger's inviting cross with barely two minutes gone.

Analysis

Image of Dan O'HaganDan O'HaganBBC Match of the Day commentator
"What a day for Michael Laudrup's Swansea. A 3-0 win on the back of last week's success. Two games played, two wins, good wins, big wins. West Ham were undone by basic first half errors."
But the home side slowly got to grips with the game and they went ahead on 20 minutes through Rangel.
Nathan Dyer found the full-back in the penalty area and the Spaniard's low drive across the face of goal squirmed under the body of Jaaskelainen and into the net.
Nine minutes later Swansea doubled their lead following another West Ham mistake.
Wales defender Collins's backpass to his goalkeeper fell short and striker Michu capitalised and applied the simplest of touches for his third goal of the season.
West Ham had offered little, but debutant Jarvis went close for the visitors when his volley on the turn was well saved by Michel Vorm.
Swansea were playing with belief and continued to push forward with left-back Neil Taylor forcing a finger tip save from Jaaskelainen after a marauding run upfield.
Play media
Allardyce laments 'disastrous' mistakes
West Ham finished a poor first half strongly and Carlton Cole, who had been largely isolated up front, had a header cleared off the line in stoppage time.
Swansea's pace continued to cause problems in the second half and Graham flashed an effort wide of Jaaskelainen's left hand post after being played in by Dyer.
A ferocious Jonathan de Guzman free-kick flashed across the face of the West Ham goal before Swansea scored a third on 64 minutes.
Graham atoned for his earlier miss when he finished off a fine Swansea move by scoring from close range from Wayne Routledge's low cross.
Home goalkeeper Vorm was rarely troubled and he comfortably dealt with substitute Ricardo Vaz Te's low free-kick.
But the Hammers could do little to stop a Swansea side who have shown their early season intent under new manager Laudrup.

LINEUP, BOOKINGS (6) & SUBSTITUTIONS (6)

Swansea City

  • 01 Vorm
  • 03 Taylor (Davies - 84' )
  • 04 Chico Booked
  • 06 Williams
  • 22 Rangel Booked
  • 07 Britton
  • 09 Michu
  • 12 Dyer
  • 15 Routledge (Moore - 81' )
  • 20 De Guzman (Agustien - 75' )
  • 10 Graham

Substitutes

  • 25 Tremmel
  • 05 Tate
  • 33 Davies
  • 26 Agustien
  • 27 Gower
  • 14 Dobbie
  • 19 Moore

West Ham United

  • 22 Jaaskelainen
  • 02 Reid Booked
  • 03 McCartney
  • 05 Tomkins (Vaz Te - 46' )
  • 19 Collins Booked
  • 20 Demel
  • 04 Nolan Booked
  • 07 Jarvis
  • 16 Noble
  • 21 Diame (Diarra - 69' )
  • 09 Cole Booked (Maiga - 62' )

Substitutes

  • 13 Henderson
  • 17 O'Brien
  • 14 Taylor
  • 23 Diarra
  • 08 Maynard
  • 11 Maiga
  • 12 Vaz Te
Ref: Atkinson
Att: 20,424