Following this Cup defeat by four tries to two at Billesley Common in Birmingham, the Titans will struggle to make the knock-out stages.
The Clifton Lane club are on six points and third in their group behind Leinster A and Moseley, who must be beaten in South Yorkshire next Sunday if Rotherham are to make any progress with three games remaining.
Failing to take advantage in the first half with the wind behind them, Rotherham managed one try by centre Joe Barker.
Moseley’s pack in the second period showed how to exploit the wind and set up several threatening positions from which they scored three more tries.
Although the Titans were outplayed, they demonstrated some character by fighting back in the second half when flanker Max Argyle added a second try.
Rotherham coach Mark Jones said: “We didn’t get enough points in the first half when we had a strong wind. The second half was difficult for us and Moseley held on to the ball well.
“Their set-piece was good and while we played some decent rugby in patches, the improvement we saw at London Scottish wasn’t built on.
“I thought centre Jack Hayes and second-row Toby Salmon stood out as did scrum-half Luke Carter when he came on in the second half.”
Moseley: Collins, Evans, King (Caves 73), Pinches, Armstrong, Foley (Penn 66), Brazier (Mitchell 62), Warren(Hobbs-Awoyemi 40), Tolmie, Gardiner, Casson (Flagg 70), Onojaife, Lawrence, Bercis, Brightwell.
Rotherham Titans: Scanlon, Rath, Hayes, Barker, Wilson, Goodwin (Jones 64), White (Carter 58), Cromie (Hislop 40), C Maddison (Cromie 66), Tampin (Elliot 80), Holmes, Salmon, Argyle, Gilmour (Calladine 58), Cree (B Maddison 58).
Referee: A Jones (Wales).