Slaven Bilić's side were dominant from the off and got their just rewards with Manuel Lanzini showing some brilliant solo skill to make good of his chance on goal.
Despite their good start, Fulham found their way back into the match late on with a goal from youngster Ryan Sessegnon.
Nonetheless, The Hammers' quality shone through in the end as they scored a second goal to peg the Championship side back.
West Ham dominant in the first-half as they record their first win of pre-season
The Premier League outfit came out of the blocks faster than their opponents, with Sofiane Feghouli making a dangerous run down the wing before cutting inside dangerously. Unfortunately, he couldn't quite link up with his teammate Fletcher in the middle of the park.
However, it wasn't long before the striker got himself on the scoresheet. Lanzini, the standout performer of West Ham's pre-season so far, managed to impressively wriggle himself into space with a drop of the shoulder. The Argentine finished it off with an accurate drive into the bottom left-hand corner from 15 yards out.
Fulham could easily have found themselves level moments later but for a terrific save from Darren Randolph. The goalkeeper got down well with a reaction save to deny Sone Aluko after Floyd Ayite pulled the ball back into a dangerous area.
Bilić's side were the ones to double their lead however. Just before the break, Fletcher capitalised on a mistake from David Button after he tried to deal with an uncomfortable backpass. That left the West Ham player with a very easy finish into an open net.
Fulham fightback not enough to stop Bilic taking the spoils
Despite the scoreline, Fulham remained involved in the contest, benefitting from Bilić's ten changes at the half-time interval. Josh Cullen was the only player remaining from the starting eleven.
A fast break on the 67 minute mark gave the Cottagers a way back into the match after Cauley Woodrow wriggled his way into a shooting chance. Nonetheless, the youngsters effort was too close to Adrian, who comfortably gathered the ball into his body. A huge let off for The Hammers.
Fulham had another chance to level the scoreline with just nine minutes left on the clock. Aluko burst into the danger area, poking the ball toward Sessegnon. This time they made good of the chance, with the left-back nodding the ball past the onrushing goalkeeper with the help of a deflection off Reece Burke.