Gareth Taylor's side needed to avoid defeat in order to secure passage to European football next season, and achieved that with a dominant performance at the Select Car Leasing Stadium.
Lauren Hemp opened the scoring in Berkshire with a well-taken goal before Bunny Shaw doubled our advantage heading into the half-time break.
City were quicker out of the traps, but early chances from Georgia Stanway and Shaw were unable to hand us the advantage.
As the half-hour mark approached, we came the close through Hemp, who had switched to the right-flank, cutting inside and firing at goal from a tight angle but only finding the side netting.
However, just a few minutes later, our breakthrough did come through that very same avenue, as Hemp brought down a chipped through ball and fired home with her second touch, giving us the lead and calming the nerves in Berkshire.
And with five minutes to go in the first half, we secured a crucial second as Weir latched onto Hemp's through ball, getting to the by-line to poke back across the face of goal and into the path of Shaw who side-footed home from close range, earning some much needed breathing space heading into half-time.
Into the second 45, City continued to control the tempo of the game, almost increasing our lead in the opening seconds when Hemp failed to connect with a low pass across the face of goal.
Deanne Rose was providing a threat for the hosts on the counter-attack, particularly down the left-hand-side, but our defence stood strong to nullify the threat of the Canadian winger.
Chloe Kelly came close, cutting onto her left foot and unleashing a well-hit strike that looked destined for the top corner, only for Reading keeper Grace Moloney to claw the effort away with a fine save.
However, with eight minutes to go, we did get our third when White, who had only been on the field for a few minutes, headed home a corner, down into the ground and beyond Moloney.
And a fourth would follow soon after when fellow substitute Hayley Raso burst through in the closing stages and was brought down by inside the area, leaving the referee with no choice but to point to the spot.
Greenwood stepped up, sending the keeper the wrong way for our fourth and final goal of the afternoon, capping off a fine performance and sealing our 13th win in a row to ensure we will be heading on the European trail next season.
WHAT IT MEANS
Avoiding defeat in Berkshire ensured that we have secured 3rd place in the FA Women's Super League, and qualification for next season's UEFA Women's Champions League.
A point would've been enough for us to ensure we could not be overtaken by rivals Manchester United, who lost 4-2 to WSL champions Chelsea.
We will now face the newly-crowned champions in the Vitality Women's FA Cup final at Wembley Stadium next Sunday.
HOW WE LINED UP
Keira Walsh provided defensive cover from midfield, with Stanway and Weir selected to play more advanced roles.
Shaw lined up as the City striker, and she was flanked by Kelly on the right and Hemp on the opposite flank.
Starting XI: Roebuck, Bronze, Kennedy, Greenwood (C), Blakstad, Walsh (Coombs 79'), Stanway, Weir (Losada 73'), Kelly (Raso 73'), Hemp, Shaw (White 80').
Subs: Keating, Taieb, Angeldahl, Mace.
Starting XI: Moloney, Bryson, Evans, Rose, Eikeland (Primmer 82'), Dowie, Harding (C), Cooper, Rowe (Peplow 82'), Vanhaevermaet (Troelsgaard 73'), Woodham.
Subs: Stewart, Poulter, Roberts.
• City have won 21 of our last 23 games in all competitions, including our last 13 in succession with a 45-5 aggregate score.
• We have scored 110 goals in the 2021/22 season so far.
• City are unbeaten in all bar one of our 12 FA Women’s Super League games against Reading (W9, D2) and have never lost an away FA WSL match against them.
• Gareth Taylor's side have won 15 of our last 18 away FA WSL matches.
City complete our season with a mouth-watering FA Cup Final clash with Chelsea at Wembley Stadium on Sunday 15 May (14:30). Tickets are on sale.
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