Both shows launched last Monday night head to head, with Big Brother narrowly beating its rival.
However Love Island took the lead on Tuesday, and continued throughout the week as the two shows aired separately with Love Island at 9PM on ITV2 and Big Brother at 10PM on Channel 5.
Last night they clashed once again as both reality series saw their first evictions and this time it was Love Island that narrowly won out.
1.1 million watched the ITV2 series - a drop of 200,000 on Thursday's show - compared to 1 million for Big Brother.
Elsewhere yesterday, coverage of the 2017 Election Result saw 1.6 million viewers watching BBC One from 2AM compared to 320,000 for ITV. Later on in the morning, 3.1 million had BBC One from 7AM compared to 1.1 million watching Good Morning Britain on ITV.
In the evening, in the soap ratings, EastEnders had 5.2 million viewers on BBC One, narrowly beating Emmerdale's 5.1 million over on ITV. Coronation Street had a commanding lead over both with 6.4 million and 6.1 million for its two episodes.
In the 9PM hour, a Have I Got News For You Election Special had 4.3 million viewers on BBC One against The Last Leg Special on Channel 4 which had 1.5 million.
Also on Channel 4, Gogglesprogs kicked off its new series with a million viewers.