Robinson almost doubled the advantage 10 minutes before the break, her fine press catching out the goalkeeper but she couldn’t quite find a teammate with the goal gaping.
The Reds then missed a gilt-edged opportunity when McBeth sent Sophie Andrews in on goal but the ‘keeper was out well to deny her.
Sheffield United had shown little but Eva Spencer needed to make a solid save before the break to keep the 1-0 advantage intact.
LFC Women PGA head coach Simon O’Neill brought on Maddy Duffy in midfield and Izzy O’Connor wide on the right for the second half, and both repaid his faith with eye-catching displays.
The two combined four minutes after the break for the latter’s cross to be controlled and finished by Bermingham in the middle for a two-goal lead.
A third followed on 56 minutes with Duffy again involved. Her pass put McDonald in on goal and she got there just before the advancing ‘keeper to score off the post, having switched from left wing-back to striker at the break.
It was generally one-way traffic but United kept working and reduced the deficit halfway through the second period, bundling in a header from a left-sided corner to offer them some hope of an unlikely comeback.
Duffy remained influential, however, and she was denied by a good save as the Reds looked to restore their three-goal cushion.
McDonald showed tons of pace to outstrip the defence but she couldn’t find an unmarked teammate for a tap-in in the middle.
The Reds were determined to have the final say and McDonald delivered it inside the final five minutes, controlling an excellent cross from the industrious Olivia Maddocks to complete the scoring.
Reflecting on the season, O’Neill told Liverpoolfc.com: “Our season started slowly with some of the transitioning U16s taking time to get used to the physicality of the U21s, which is understandable.
“But certainly since Christmas it’s been really good – they’ve won 13 in a row and nine in a row in the league.
“They deserve to win this title. Lots to work on and get better at, especially out of possession. But in possession we’re a really good team who control the ball well and make some good decisions.”