They will face the winners of Thursday’s second semi-final between Vietnam and Malaysia.
Chanathip Songrasin opened the scoring in the 7th minute and brace from Kroekrit Thawikan in the 57th and 87th minutes secured the victory.
In the absence of Kirati Keawsombut and Adisak Kraisorn, missing through injury and suspension respectively, Chanthip played upfront and with great effect.
Thailand were on the offensive from the outset, and Chanthip made the pressure count in the eight minute when he slotted home after Narubadin Weerawatnodom had headed a Kroekrit cross in his direction.
The home side were having great success down the right, with Philippines left-back Daisuke Sato substituted after picking up an early yellow card, with a red seeming likely if he continued. Martin Steuble dropped back to replace Sato, but would have no better of a time.
Philippines would not have a chance of note until the 40th minute, with Patrick Reichelt getting on the end of Paul Mulders' delivery, but his header was straight at Kawin Thammasatchanan.
Thailand should have made it two before the break when Prakit Deeprom was through one-on-one with Patrick Deyto in the Philippines goal. However, his attempt to set up Charyl Chappuis for the tap-in went astray.
Philippines came out of the blocks strongly after the interval, but were unable to make the most of a brief spell of pressure and would pay the consequences.
On 57 minutes Kroekrit doubled the host's advantage as he held off one defender before firing past Deyto.
Matters got even more desperate for Philippines on 82 minutes when Steuble was sent off after picking up a second yellow card.
Kroekrit put the result beyond any doubt four minutes later, controlling a Sarach Yooyen through ball before firing it into the bottom corner.
Thailand: Thamsatchanan – Notechaiya, Kesarat, Phukhom, Weerawatnodom; Yooyen, Deeprom, Thawikan, Songkrasin, Charyl Chappuis; Thosakrai
Philippines: Deyto – Aguinaldo, Robert Gier, Sato (32’ Reichelt), Rota (70’ Hartmann); Lucena, Manuel Ott, Steuble, Phil Younghusband, Bahadoran; Mulders (72’ Greatwich)